MCUs - where to look for cheap universal workhorses ( 5V and 3V options) ? - Page 1
Forum section: electronics / general

author: Adrian_Taylor333
author_rank: Regular Contributor
timestamp: August 14, 2025, 01:23:14 am
content: It seems that ARM based stuff has flooded everything else.Where would one look for general purpose MCU options with lowest price in decent package ( 64-pin or more) with best bang/$ ratio, both with lines that can do 5V and 3V models ?Also, which would be most popular Chinese options, besides obvious one - SiFive ?AFAIK, current options that I'm aware of:- AVR is decent, often with better peripherals than PIC and FAR better CPU core. It even has a couple models with 2 concurrent I/O voltage options.- PIC16/18 lines - ghastly stuff, but still there are some models with unique combo of peripherals and working voltages. Used to be cheapest MCUs, not anymore- TI MSP430 lines - not a speed champion, but often enough cheapest option that still fits the need- some Cypress lines, based on prehistoric 8051Any other ideas ?Are there lines that can occasionally be got at a specially great price due to surplus quantities etc ?

author: brucehoult
author_rank: Super Contributor
timestamp: August 14, 2025, 01:38:22 am
content: WCH, obviously.Most of their MCUs come in packages with fewer than 64 pins, but there is:- CH32V305/CH32V307 available in TSSOP​20, QFN​28, LQFP​48, LQFP​64, QFN​68, LQFP​100Official WCH store:https://www.aliexpress.com/item/1005004329064488.htmlUnfortunately they run only on 2.5V or 3.3V.WCH's smaller MCUs such as CH32V003 and CH32V103 can run on up to 5.5V but the 200 and 300 series are 3.3V maximum.The 103 is available in LQFP64M, LQFP48 so maybe could meet your needs.https://www.aliexpress.com/item/1005004578534007.html

author: PCB.Wiz
author_rank: Super Contributor
timestamp: August 14, 2025, 03:23:58 am
content: Quote from: Adrian_Taylor333 on August 14, 2025, 01:23:14 amIf you want 64+ pins, you are moving out of the "cheap universal workhorse" area, into something rather larger.If you want 64+ pinsand5V that's thinning the field out significantly, a quick look at WCH, shows only CH32F103/CH32V103 with 5Vand64 pins.eg Plenty of 5V parts with lower pin counts and plenty of 100pin parts at 3v3.Nuvoton have a few 5V high pin count parts. their M7 KM1M7A is 100/144 pins, 160Mhz 5V, and in M4 they have M471 series (64/100/128 pins 120Mhz 5V) and KM1M4BF (64/80/100 pins 120MHz 5V)Recent parts from Renesas like RX660 with RXv3 core support 5V 120 MHz & 48-pin to 144-pin.tho parts like the Pi PICO 2 claims 5V tolerant with some caveats. Maybe that is good enough ?

author: Adrian_Taylor333
author_rank: Regular Contributor
timestamp: August 14, 2025, 05:18:48 am
content: Quote from: PCB.Wiz on August 14, 2025, 03:23:58 amNot really. 64 pins seems to be sweet spot for 8-bit micros. Below that the price is dominated by other elements ( why pay a bit less for much lower capabilities ?), above that price skyrockets.I'm looking for something vanilla that can be bought at whole tray qtys and used for whatever. MCU tire patch kit, so to say.Such workhorse used to be PIC16C1527. Atrocious core, but cheap as chips and choke full of usual peripherals (A/D,I/O,PWM,USARTs, SPIs, I2C, timers etc etc).And with a bit of imagination, one could emulate EEPROM in it. PIC16F1947 was the same deal, only with (emulated?) EEPROM.There used to be similar PIC32 line, which was meant to offer 32-bit MIPS core for 8-bit price and capabilities, sans 5V I/O.I've just checked and that whole line was replaced with PCI32AK line, which is much faster (200MHz), but basically the same deal.WHich is kind of pointless as nowadays ARMs dominate whole segments.Once one is out of 5V land, it's kind of hard to justify anything except ARM.Quote from: PCB.WizI like RISC-V, but the product portfolio , even in low cost segment is pretty thin and I don't think many will be gunning for 5V segment.Quote from: PCB.WizInteresting, but quite niche products.These are likely not ultracheap, so not something I'd buy on metric ton and use through the eternity.Quote from: PCB.WizToo niche for my taste. And to mercurial. They've fumbled up 5V I/O and never noticed. And it took them eternity to fix it.ANd they could just as easily change or replace whole line - which is a single product.

author: krho
author_rank: Regular Contributor
timestamp: August 14, 2025, 05:19:37 am
content: How many 5V compatible pins would you need. Wouldn't be better to use level shifters? We use them all the time as our IO is at 1.8V and not every chip that we use goes that low.

author: Adrian_Taylor333
author_rank: Regular Contributor
timestamp: August 14, 2025, 05:32:24 am
content: Quote from: krho on August 14, 2025, 05:19:37 amPreferably all of them. In many simple small designs having level shifters is not that cheap or practical.One can get quite decent micro for less than $2 these days.Having extra level shifters, PSU outputs etc etc significantly changes things.

author: westfw
author_rank: Super Contributor
timestamp: August 14, 2025, 06:43:08 am
content: QuoteI don't think that Microchip ever "discontinued" a product line...The new AVRmmmDA64 and AVRmmmDB64 seem like nice 8bit 5V parts that meet your requirements, but I don't think there are any recent chips larger than 64pins.The ST32F series, and their many almost-copycats seems a natural for 3V parts. It's almost as if you have second sources!

author: Adrian_Taylor333
author_rank: Regular Contributor
timestamp: August 14, 2025, 07:44:46 am
content: Also ST's M8S line looks good.It has plenty of cheap micros and even some in 80-pin package with not much price uplift.

author: Siwastaja
author_rank: Super Contributor
timestamp: August 14, 2025, 07:48:58 am
content: 5V is getting really limiting. Consider carefully if you truly need it. Most other ICs you would communicate with accept 3.3V logic nowadays. A lot of stuff is also still TTL levels (even when built in CMOS technology), which interfaces fine with 3.3V CMOS. In the rare cases of actually needing 5V CMOS, you can level-shift externally.

author: Adrian_Taylor333
author_rank: Regular Contributor
timestamp: August 14, 2025, 07:50:19 am
content: Quote from: westfw on August 14, 2025, 06:43:08 amAVR64DBxx looks great. Capable core, and above else dual-voltage I/O with internal level shifters is a killer feature.PIC line has a chio or two with level shifter, but that can't come close to that AVR line.

author: Adrian_Taylor333
author_rank: Regular Contributor
timestamp: August 14, 2025, 07:52:17 am
content: Quote from: Siwastaja on August 14, 2025, 07:48:58 am5V is still awesome for many simple roles.It offers great EMI immunity with much less of a need for shielding, expensive PCB etc etc.It also has much beefier, rugged I/Os.it can drive nice MOSFET or LED much easier etc etc.And plenty of 5V parts can work at 3V or even lower.

author: Psi
author_rank: Super Contributor
timestamp: August 14, 2025, 08:10:30 am
content: Is WCH stable enough to use in a professional product?

author: woofy
author_rank: Frequent Contributor
timestamp: August 14, 2025, 08:22:38 am
content: I think I would suggest you look at your starting premise here, in wanting a "cheap universal workhorse". In my experience there is no such thing. Every job will have a different spec' and you will always be wanting that "special" peripheral. Instead I would chose a product family with good toolchains and learn that. We use microchip a lot and can quickly get a new uC up and running as the workflow is the same. For a personal choice of family I would choose Microchip or ST.However the middleware from both can be a vertical learning curve. Another option is to go with a toolchain such as Arduino. You are not limited to AVR's any more but can use a wide range of controllers from many companies. The libraries available cover just about anything you want to do.

author: fchk
author_rank: Frequent Contributor
timestamp: August 14, 2025, 08:27:23 am
content: For 5V projects I often use dsPIC33EV. It's fast (70 MHz), has a decent amount of memory and is a rather simple architecture. Much easier than STM32 du to a much simpler clock tree. And the CPU core is not a foreign building block but an integral part of the hole system. RAM and SFRs are interfaced directly to the core, not through an asynchronous peripherial bus.For 3V systems you would then use the matching dsPIC33EP series.And PICs are easy to get, and they will not disappear overnight given Microchip's past records. Expect then to be around the next 20 years.

author: Adrian_Taylor333
author_rank: Regular Contributor
timestamp: August 14, 2025, 08:29:57 am
content: Quote from: woofy on August 14, 2025, 08:22:38 amNot my experience at all.Chasing idela MCU combos is for high-volume series and contracts etc.For mere mortals, time and place of purchase can make much bigger difference than anything else.For me, it makes sense to get a tray of chips with nice common denominator and use them as digital patches for problems at hand.For 8-bitters, that choice usually falls on 64-pin QFP chips that can do work off 5V ( ideally 2-5V etc), have reasonable amount of FLASH and RAM and usual set of peripherals for a general-purpose class. Dual-voltage I/O is an icing on that cake.For 32-bitters, it's hard to get past ARMs, something like M3/M4 etc, QFP80/100, usual peripherals + USB and maybe CAN,LIN and Ethernet.

author: Adrian_Taylor333
author_rank: Regular Contributor
timestamp: August 14, 2025, 08:32:30 am
content: Quote from: fchk on August 14, 2025, 08:27:23 amdsPIC is much more expensive, overkill for me. It's meant for specific motor-control and similar applications, where one needs speed, response time and DSP capability as well as EMI robustness.Which has its price.MOst of the simple stuff, especially that I interface with 5V power or I/O is outside of that category.

author: brucehoult
author_rank: Super Contributor
timestamp: August 14, 2025, 08:57:28 am
content: Quote from: Psi on August 14, 2025, 08:10:30 amStable in what way?The chips work great. The company has been around since 2004 and their CH340 USB-to-UART chips have been going into a vast array of "professional" products since 2013 (?) or so, often replacing the despised FTDI chips.That alone is probably enough to fund the company :-)

author: nctnico
author_rank: Super Contributor
timestamp: August 14, 2025, 09:05:49 am
content: Quote from: Adrian_Taylor333 on August 14, 2025, 01:23:14 amWhy is cheap important? A very common mistake is saving some money on parts and spending 20k+ euro extra on software engineering. If this is for a commercial project then I'd start by looking at software tooling and documentation quality of a microcontroller. That is where you'll save most of the money where it comes to development. Using cheaper parts only becomes benificial when doing production runs from 50k units or more because the software will be way more expensive to develop.If this is a hobby project, ask yourself how much is your time worth. Do you want to spend days figuring out how to get a peripheral going or spend your time to actual push the project forward?

author: brucehoult
author_rank: Super Contributor
timestamp: August 14, 2025, 09:40:35 am
content: Quote from: nctnico on August 14, 2025, 09:05:49 amThat argument kind of falls apart when the cheapest $0.10 (8 pin) flash-based MCUs available are 32 bit 48 MHz with excellent support from both GCC and LLVM toolchains and their peripherals are faithful clones of the industry-standard (?) STM32 ones. And the compatible family of chips goes up to 64 and 100 pin packages with a lot more RAM and flash and MHz and USB and CAN and built in packet radios and ...Sure I agree, avoid the $0.03 OTP Padauk chips with an awful slightly modified PIC12 (8 bit) instruction set. THAT level of saving is very unlikely to be worth it.Also the PUYA PY32F002A can be around $0.08 and is a Cortex M0 (good), but unlike WCH, Gigadevice and others the peripherals (and pinouts) are not clones of STM32 or other popular MCUs, so they also have higher development effort.

author: Psi
author_rank: Super Contributor
timestamp: August 14, 2025, 09:51:03 am
content: Quote from: brucehoult on August 14, 2025, 08:57:28 amI've not looked into them, but for some reason i was under the impression they were slightly dodgy STM32 clones with lots of bugs.But from googling it seems i'm wrong.I retract my question.

author: langwadt
author_rank: Super Contributor
timestamp: August 14, 2025, 09:55:18 am
content: Quote from: brucehoult on August 14, 2025, 09:40:35 amfor a hobby or low volume project how many minutes of time do you have to use before the difference between a $0.10 mcu and $2 mcu doesn't matter ?

author: Adrian_Taylor333
author_rank: Regular Contributor
timestamp: August 14, 2025, 10:06:04 am
content: Quote from: nctnico on August 14, 2025, 09:05:49 amIf this was a commercial project, I obvioulsy wouldn't be asking this kind of question here.And cheap is important, even for hobbyist and small project.In those, even when one values his time less than a paid professional, reducing the time spent on learning curve for many MCUs and their SDKs can be a big deal.Especially if one can make choose a decent common denominator and order a tray of MCUs to be used for common general-purpose applications.Quote from: nctnicoIn most of my projects I want to learn by understanding and doing things efficiently is essential part of the process.Using parts and tools efficiently is main part for me.So within those constraints this makes sense for me. I minimize the price for those kind of parts through batch order, minimize the learning curve by doing it once for the part and minimize code writing/debugging effort by reusing libraries or source code snippets for the same MCU or the same family.

author: nctnico
author_rank: Super Contributor
timestamp: August 14, 2025, 10:25:39 am
content: Quote from: brucehoult on August 14, 2025, 09:40:35 amFFS! STM32 are amongst the worst documentated microcontrollers around with lots of quirks to spare. If you want to waste time & money, go for STM32. Been there, done that. Fortunately I got to spend other people's time and money dealing with that mess. The reason STM32 got popular is because many people are totally clueless about cost of software development where on the other hand you can put an exact price on hardware. So saving 10 cents on the microcontroller while dreaming of a production run of 100k units looks really nice. But it is living in a dream world visited by many. I've seen this going wrong soooo many times. Penny wise, pound foolish.

author: Siwastaja
author_rank: Super Contributor
timestamp: August 14, 2025, 10:29:31 am
content: Quote from: Adrian_Taylor333 on August 14, 2025, 07:52:17 amI'm afraid none of this is true at all, sounds totally made-up myths.

author: nctnico
author_rank: Super Contributor
timestamp: August 14, 2025, 10:42:54 am
content: Quote from: Adrian_Taylor333 on August 14, 2025, 10:06:04 amIn that case look at NXP's LPC series ARM Cortex microcontrollers. Their documentation is excellent and their peripherals make sense. If you go into the user manual every section on a peripheral starts with a checklist telling you exactly which clocks need to be enabled and how to initialise the peripheral. There is no searching or second guessing needed. Also, the peripherals are shared amongst the entire line so you only need to write peripheral drivers once and you can hop between a huge amount of different microcontrollers. I have been using these for 20+ years in lots of projects.

author: brucehoult
author_rank: Super Contributor
timestamp: August 14, 2025, 10:57:01 am
content: Quote from: langwadt on August 14, 2025, 09:55:18 amAnd what if the minutes of time is identical because the $0.10 chip is equally well documented and easy to use?

author: peter-h
author_rank: Super Contributor
timestamp: August 14, 2025, 11:05:36 am
content: See here for my Chinese "32F407" testshttps://www.eevblog.com/forum/microcontrollers/opinions-on-st-32f407vgt6-versus-gigadevice-gd32f407vgt6/But ST sell their 407 very cheaply, presumably due to the chinese competition, so no need for chinese at all, and you avoid the political risk. Also therearedifferences even with the best one (last post in the above link).But only very high volume products need sub-$1 CPUs, so the whole devt tool proposition changes. A hobbyist should not care about the CPU cost.

author: brucehoult
author_rank: Super Contributor
timestamp: August 14, 2025, 11:11:05 am
content: Quote from: nctnico on August 14, 2025, 10:25:39 amOh, I see from your later message that you want to get into an STM32 vs NXP LPC pissing match.I confess that I don't have the experience with both to be able to comment. My experience is with STM clones from both WCH and Gigadevice, which I have not found difficult.Grok says that the higher end STM32 are less beginner-friendly than NXP LPC (but better for professionals, with more scope), but the STM32F0/L0 are even easier than NXP LPC. It also suggests SAM21D os being easier to transition to if you're familiar with the company's PIC or AVR lines, which might well be true, idk.I have no doubt that MXP are easier FOR YOU with 20 years experience with them behind you, and would never suggest that you change. But you are not OP, and they are not you.

author: SpacedCowboy
author_rank: Frequent Contributor
timestamp: August 14, 2025, 11:18:52 am
content: Coming from working with STM32 and moving over to NXP for a project, I really disliked the NXP documentation, stuff was never where I expected it to be and things took longer.Overall, though, it was just me being unfamiliar with the different hardware/docs and not being able to leverage all the knowledge I'd accumulated to date. I never did go back to NXP, but that's more a consequence of my life than anything else.In any event, these days I prefer the RP2xxx series unless you need loads of pins. They're (a) cheap, (b) powerful, (c) over-clockable to an insane degree, (d) dual-core, and (e) have the PIO with DMA support built in to handle all the tricky interfacing.The only black mark against them is being single-source IMHO, but my projects (since retiring) aren't really affected by that sort of thing.

author: Adrian_Taylor333
author_rank: Regular Contributor
timestamp: August 14, 2025, 11:39:26 am
content: Quote from: Siwastaja on August 14, 2025, 10:29:31 amIf it was just a myth, there would be no 5V version of dsPIC, or NXP's newest MCX -E / M4F/M7 - based micros that can run on 5V.

author: brucehoult
author_rank: Super Contributor
timestamp: August 14, 2025, 12:07:21 pm
content: Quote from: Adrian_Taylor333 on August 14, 2025, 11:39:26 amYou don't think people made 5V MCUs initially because 74LS is 5V, and more recently continue to because it's convenient to be powered from USB without a regulator?

author: Siwastaja
author_rank: Super Contributor
timestamp: August 14, 2025, 12:16:10 pm
content: Quote from: Adrian_Taylor333 on August 14, 2025, 11:39:26 amSounds like some marketing gimmick to me. They advertise them as being robust, reliable and industrial also when ran at 3.3V, which totally blows up the argument of this "robustness" actually having anything to do with the 5V supply.3.3V parts are used in every possible critical field all the time.If you want a "cheap universal workhorse", I suggest youavoidthese.

author: Rafiki
author_rank: Contributor
timestamp: August 14, 2025, 12:37:42 pm
content: Quote from: Adrian_Taylor333 on August 14, 2025, 10:06:04 amSo I misunderstand your subject a bit. Maybe you should have been a bit clearer about that from the beginning. If you ask for 'cheap' most people think of professional use and 20k/year at least. For a hobbyist it does not make any sense to safe an € per chip when he looses days stumbling over the pitfalls and documentation shortcomings of the f.i. STM32.QuoteThese are reasons why I now stick to EFM32xx since about 15 years for most of my private projects. Only a few PIC24 anymore. No PIC16, no PIC32, no 8051 (clones) and no Atmega anymore. I switched from G to TG and LG and GG and PG series for different reasons. Luckily the peripherals are often the same. Sometimes at least the library is compatible. But of course f.i. for some newer chips when you wanna use the new features you have to adapt. JG/PG f.i. have 5V tolerant IOs. And believe me if you've done something with a 32bit M3/M4 with a lot of FLASH and RAM and a lot of peripherals you never want to go back to some 8 or 16 bit device with limited peripherals. Not for hobby projects.

author: SiliconWizard
author_rank: Super Contributor
timestamp: August 14, 2025, 12:54:07 pm
content: What exactly is a "universal workhorse"?

author: brucehoult
author_rank: Super Contributor
timestamp: August 14, 2025, 01:34:38 pm
content: Quote from: Rafiki on August 14, 2025, 12:37:42 pmOnce again: those are not the only options, or even correlated.RP2040 are $1 qty 1, or $0.80 qty 500, and are rather well documented and easy to use.Resources such ashttps://github.com/cnlohr/ch32funmake the entire WCH range ... down to the $0.10 chips, but also the more powerful ones, very easy to get started with and use, even for MCU beginners (you do need to know C programming).WCH also provide an Arduino library and IDE integration for them, for even more n00b users.https://github.com/cnlohr/ch32fun/blob/master/examples/blink/blink.cCode:#include "ch32fun.h"#include <stdio.h>// use defines to make more meaningful names for our GPIO pins#define PIN_1 PD0#define PIN_K PD4#define PIN_BOB PD6#define PIN_KEVIN PC0int main(){SystemInit();funGpioInitAll(); // Enable GPIOsfunPinMode( PIN_1, GPIO_Speed_10MHz | GPIO_CNF_OUT_PP ); // Set PIN_1 to outputfunPinMode( PIN_K, GPIO_Speed_10MHz | GPIO_CNF_OUT_PP ); // Set PIN_K to outputfunPinMode( PIN_BOB, GPIO_Speed_10MHz | GPIO_CNF_OUT_PP ); // Set PIN_BOB to outputfunPinMode( PIN_KEVIN, GPIO_Speed_10MHz | GPIO_CNF_OUT_PP ); // Set PIN_KEVIN to outputwhile(1){funDigitalWrite( PIN_1, FUN_HIGH ); // Turn on PIN_1funDigitalWrite( PIN_K, FUN_HIGH ); // Turn on PIN_KfunDigitalWrite( PIN_BOB, FUN_HIGH ); // Turn on PIN_BOBfunDigitalWrite( PIN_KEVIN, FUN_HIGH ); // Turn on PIN_KEVINDelay_Ms( 250 );funDigitalWrite( PIN_1, FUN_LOW ); // Turn off PIN_1funDigitalWrite( PIN_K, FUN_LOW ); // Turn off PIN_KfunDigitalWrite( PIN_BOB, FUN_LOW ); // Turn off PIN_BOBfunDigitalWrite( PIN_KEVIN, FUN_LOW ); // Turn off PIN_KEVINDelay_Ms( 250 );}}Easy enough?Or, if you prefer, the same header offers even more bare metalhttps://github.com/cnlohr/ch32fun/blob/master/examples/blink_raw/blink_raw.cCode:#include "ch32fun.h"#include <stdio.h>int main(){SystemInit();// Enable GPIOsRCC->APB2PCENR |= RCC_APB2Periph_GPIOD | RCC_APB2Periph_GPIOC;// GPIO D0 Push-PullGPIOD->CFGLR &= ~(0xf<<(4*0));GPIOD->CFGLR |= (GPIO_Speed_10MHz | GPIO_CNF_OUT_PP)<<(4*0);// GPIO D4 Push-PullGPIOD->CFGLR &= ~(0xf<<(4*4));GPIOD->CFGLR |= (GPIO_Speed_10MHz | GPIO_CNF_OUT_PP)<<(4*4);// GPIO D6 Push-PullGPIOD->CFGLR &= ~(0xf<<(4*6));GPIOD->CFGLR |= (GPIO_Speed_10MHz | GPIO_CNF_OUT_PP)<<(4*6);// GPIO C0 Push-PullGPIOC->CFGLR &= ~(0xf<<(4*0));GPIOC->CFGLR |= (GPIO_Speed_10MHz | GPIO_CNF_OUT_PP)<<(4*0);while(1){GPIOD->BSHR = (1<<0) | (1<<4) | (1<<6);// Turn on GPIOsGPIOC->BSHR = (1<<0);Delay_Ms( 250 );GPIOD->BSHR = (1<<16) | (1<<(16+4)) | (1<<(16+6)); // Turn off GPIOsGPIOC->BSHR = (1<<16);Delay_Ms( 250 );}}GDB works. Printf() Just Works, either via UART or the SWD ... your choice.https://github.com/cnlohr/ch32fun/blob/master/ch32fun/ch32fun.hCode:#define FUNCONF_USE_DEBUGPRINTF 1#define FUNCONF_USE_UARTPRINTF 0#define FUNCONF_NULL_PRINTF 0 // Have printf but direct it "nowhere"

author: nctnico
author_rank: Super Contributor
timestamp: August 14, 2025, 01:40:50 pm
content: Now go and write your own internal flash driver because the HAL provided one doesn't suit the project

author: brucehoult
author_rank: Super Contributor
timestamp: August 14, 2025, 01:48:05 pm
content: Quote from: nctnico on August 14, 2025, 01:40:50 pmhttps://github.com/cnlohr/ch32fun/blob/master/examples/flashtest/flashtest.c

author: Chalcogenide
author_rank: Regular Contributor
timestamp: August 14, 2025, 01:52:35 pm
content: One additional entry for 5V MCUs is the WCH CH32X035 that supposedly exists in a 64 pin package with 60 GPIOs (although I have only ever seen it in <48 pin packages), has a few peripherals, and even allows you to run USB when powered at 5 V thanks to an internal regulator for the USB PHY.

author: SiliconWizard
author_rank: Super Contributor
timestamp: August 14, 2025, 02:28:50 pm
content: The SDKs provided by WCH are also a decent starting point. All source code is provided and it's easy to re-implement some of the functions if needed.As to "5V", unless you routinely work with vintage hardware and need easy ways to interface with that, or in some niche industries, I don't see the point for the average hobbyist.

author: NorthGuy
author_rank: Super Contributor
timestamp: August 14, 2025, 02:34:21 pm
content: Quote from: Adrian_Taylor333 on August 14, 2025, 05:18:48 amAnd then again PIC16F19197 with EEPROM.It all depends on the periphery you need.

author: langwadt
author_rank: Super Contributor
timestamp: August 14, 2025, 02:34:38 pm
content: Quote from: Siwastaja on August 14, 2025, 12:16:10 pmabout the only reason for 5V io I can think of is for stuff like automotive, alot of "smart fets" really need 5V drive, and many sensors are 5V and high impedance so you can't just use a resistive divider into a 3.3V ADC

author: Adrian_Taylor333
author_rank: Regular Contributor
timestamp: August 14, 2025, 02:47:40 pm
content: Quote from: brucehoult on August 14, 2025, 12:07:21 pmTrue, but 5V lines now persist mainly for other reasons, like noise immunity, driving abilities, chip robustness (larger process node that tolerates higher voltages etc), extra internal LDO for internal regulation etcetc.74LS is rare these days, even 5V mostly uses 74HC/T etc. But MOSFETs still like to be driven with decent gate voltage, many LEDs need more than 3V etc etc.

author: Rafiki
author_rank: Contributor
timestamp: August 14, 2025, 03:28:52 pm
content: Quote from: brucehoult on August 14, 2025, 01:34:38 pmYes I see your point. Lot of options are presented here already. Problem is the TO started with 'cheap' and 'universal workhorse' which contradicts for most of us I think. Then it turns out that cheap would probably not mean below 0,50€ or $ cause he's only using it for a hobby (small quantities where price doesn't really matter compared to investment in tools and time). And he compares to Microchip PICs which usually are quite expensive.Also at the beginning it was '5V and 3V'. Now it seems 5V or 5V tolerance is not an option but 5Vpower supply(output drive) is a must have. We are going circles with very unclear requirements..... Anyway I think more than a few good options are on the table. Until new requirements came up ;-)

author: PCB.Wiz
author_rank: Super Contributor
timestamp: August 14, 2025, 10:37:54 pm
content: Quote from: Adrian_Taylor333 on August 14, 2025, 02:47:40 pm5V easily dominates the small MCU market, and there wide VCC is very common 1.8-5.5V or 2.4-5.5VThere is simply no need to make 3V only MCUs at the smaller end.It is when you head to much larger packages, 64 pins and above, that core speed matters more than peripheral IO flexibility.

author: uer166
author_rank: Super Contributor
timestamp: August 15, 2025, 06:08:54 am
content: Quote from: langwadt on August 14, 2025, 02:34:38 pmI've heard this silly nonsense a lot about automotive applications that "require 5V".It's complete fiction in reality, especially for the last 15 years or so. The existence of 5V MCUs is largely a legacy decision, they have few, if any advantages. EMI wise they're objectively worse because they require a larger dv/dt swing for same frequency (comparing apples to apples).I've worked specifically on eFuses and LV vehicles systems that you're calling "smart FETs". Pretty much all were driven by 3.3V or below on the logic side.

author: Adrian_Taylor333
author_rank: Regular Contributor
timestamp: August 15, 2025, 06:28:57 am
content: Quote from: uer166 on August 15, 2025, 06:08:54 amWhy ?5V parts have internal LDO for the core, which helps insulating it from powerline fluctiations.They also tend to be built on older processes with much higher tolerances and breakdown voltages etc.All this and then some ddoesn't go away just because you power the chip with lover voltage.I've heard this silly nonsense a lot about automotive applications that "require 5V".Quote from: uer166 on August 15, 2025, 06:08:54 amIt seems that you are ingorant about HW. FETs gate knee voltage curve isn't exactly arbitrary.Having a FET with lower gate volta<ge threshold requires some tradeoffs, both within FET and outside of it.One outside tradeoff is gate ringing due to miller capacitance being more of a problem.Other MOSFETs voltage. Can't have good low-gate voltage HV MOSFET.There is a reason that HV power MOSFETs like 10V or mroe.

author: Siwastaja
author_rank: Super Contributor
timestamp: August 15, 2025, 07:03:40 am
content: Really, difference between 5V and 3.3V is just 34% for noise margin against coupled voltages. That is a totally marginal difference. So maybe if you have a design which fails EMI by 1dB would have barely passed by 34% increased noise immunity. Yet high-reliability designs commonly use any Vcore, and IO voltages down to as low as 1V.I have never used any kind of "special shielding" or "special PCB design" practices regardless of IO voltage. I hear about this idea the first time. My 3.3V designs have been simplistic and passed EMC with flying colors.If you need robust IO, then you will use something else than MCU CMOS IO pin directly exposed to the outside world! You put a transceiver (maybe CAN, maybe Ethernet, maybe RS422, maybe something else) next to the MCU.IMHO you are focusing on totally wrong thing here, concentrating on the EMC or reliability argument. 5V in modern parts is total niche and seriously limits your choice. Old 8-bit controllers are still very popular with 5V supply support (PCB.Wiz is right about them dominating), but I expect this to change within the next 10 years, with simple cheap Cortex-M0 or even some RISC-V parts replacing the markets, while a much smaller set of the absolute most popular 8-bitters remain in manufacturing, well, because of the same reasons you can still buy a 555 timer IC, supporting legacy designs.

author: PCB.Wiz
author_rank: Super Contributor
timestamp: August 15, 2025, 08:28:10 am
content: Quote from: Siwastaja on August 15, 2025, 07:03:40 amYou miss the detail that in the small MCU arena, most of those new cheap 32 bitters are offeringwide supply,that means 5V is not going anywhere, users simply have the choice of what Vcc to use.eg all of the new small parts from WCH in CH32V002 thru CH32V007, covering SOP8 thru QFN32, are all wide supply. (most recent ones are 2.5/3.3/5.0)All the PUYA MCUs from DFN8 up to even QFN64 are operating from 1.7 V ~ 5.5VYou could say that narrow supply or5V onlyparts are the ones that are fading in the small MCU arena.The physics of Blue/White LEDs is rather fundamental, and very low threshold MOSFETS only reach up to a certain current level.

author: Siwastaja
author_rank: Super Contributor
timestamp: August 15, 2025, 08:48:16 am
content: Quote from: PCB.Wiz on August 15, 2025, 08:28:10 amYou might be right. Maybe the direction of going into 3.3V-only and below is being reversed and 5V-capable designs are making a "comeback". And maybe a big part of that is battery-powered IoT with li-ion supply.I guess manufacturers finally realized that driving the MCU directly off a battery is optimal: getting rid of drop-out voltage of a regulator, hence can discharge further; removal of the quiescent current of the regulator, reduction of BOM cost. Hence, operation to 4.2V is very useful, and as such using those older process nodes that can produce max 6V ICs makes sense even today.