cheap and basic microcontroller - Page 1
Forum section: electronics / beginners

author: abhimanyu
author_rank: Newbie
timestamp: August 28, 2010, 10:10:17 am
content: hii have experience of using atmega 16/32/.. series microcontrollersi have used spi programming through usbasp and parallen db25 port, adc, i/o functions of atmeganow i need a microcontroller with the following specifications:1 adc channel 8 bit3 i/o pinseasy to make its hardware as i will not be able to purchase evaluation boardAS CHEAP AS IT CAN BEram:512 kbnon volatile flash 512 kbcan i get some suggestions

author: Simon
author_rank: Unknown
timestamp: August 28, 2010, 10:15:23 am
content: PIC 12F615 it's about the most feature full of the 12F' series without spending serious money

author: Unknown
author_rank: Unknown
timestamp: August 28, 2010, 10:34:53 am
content: Most specs are pretty basic, but 512kB ram / flash is a lot, I don't think you'll find many 8-bit micros that can do that, might have to move up to 16-bit or even 32-bit for that. Apart from that, almost any micro would do. If you have the experience and tools for AVR, I'd start looking for those, since you wouldn't need to spend as much time studying the documentation, and don't have to invest in a programmer. Apart from the RAM/flash requirements, something like an ATtiny13 or ATtiny25/45/85 would do, all are available in DIP-8. For 512kB RAM/flash, you'd probably need to look at ARM/AVR32/PIC32, which are usually not cheap or available in DIP.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: August 28, 2010, 02:06:30 pm
content: Quote from: abhimanyu on August 28, 2010, 10:10:17 amDo you really mean 512kram and rom? If so your choices are somewhat limited, and it will come with somewhat more than 4 IO pins, cost a lot more than an ATMega and definitely won't be in a DIP package..!Quote12F617 is a significant improvement on the 615 as it has self-programming and double the flash/ram for around the same price. However if youreallyneed 512 bytes RAM you'll need to look further up market. RAM is quite expensive in silicon-area terms, which is why you don't see low-end parts with lots of it.

author: Simon
author_rank: Unknown
timestamp: August 28, 2010, 02:11:56 pm
content: well I'm looking into the 12F683, what was the improvement on the '615 that the '617 made ?

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: August 28, 2010, 02:31:04 pm
content: Quote from: Simon on August 28, 2010, 02:11:56 pmSelf-programming.Flash can be updated via whatever interface your product has.Also, the 615 has no eeprom, the 617 allows storage of nonvolatile data in flash.

author: Simon
author_rank: Unknown
timestamp: August 28, 2010, 02:44:31 pm
content: cool i may look into that, I've only just done my first ISP project

author: Mechatrommer
author_rank: Super Contributor
timestamp: August 28, 2010, 03:21:55 pm
content: atTiny85...http://cgi.ebay.com.my/ATtiny85-20PU-Atmel-AVR-20MHz-PDIP-MCU-ATtiny-85-AT85-/250625114025?pt=UK_BOI_Electrical_Components_Supplies_ETif you meant 512 bytes ram n flash. 512KB is to program Windows Applicationand the processor is NOT cheap!can check herehttp://www.atmel.com/dyn/products/param_table.asp?family_id=607&OrderBy=part_no&Direction=ASC#791

author: Simon
author_rank: Unknown
timestamp: August 28, 2010, 03:27:01 pm
content: Quote from: shafri on August 28, 2010, 03:21:55 pmJeez someones taking the piss or atmel are horribly exspensive. the 12F615 is much cheaper:http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=180546121357

author: Mechatrommer
author_rank: Super Contributor
timestamp: August 28, 2010, 03:42:22 pm
content: i think that seller guy put the price too high. i agree for a 8 pin DIP, $3 is too much! thats the sad thing about atmel... less availability. not much seller to compete, and currently there are 2 sellers only in ebay (both from UK, will take hell to ship to my country)

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: August 28, 2010, 03:44:27 pm
content: even cheaperat Farnell12F617 is about half the cost of any of the 8 pin ATTinys

author: Simon
author_rank: Unknown
timestamp: August 28, 2010, 03:47:50 pm
content: Quote from: mikeselectricstuff on August 28, 2010, 03:44:27 pmlooks like PIC is the way to go then. eBay is handy for small quantities, here in the UK Farnell want a minimum order of £20 which often means I end up spending more than i planned to especially when the price breaks for higher quantities look attractive, after all I can always offload my surplus on eBay

author: Mechatrommer
author_rank: Super Contributor
timestamp: August 28, 2010, 04:00:03 pm
content: no wonder its more expensive (by several cents)... its a 20MHz capable "fetcher" compared to 12f615 5MHz "runner". the guy is already familiar with AVR instructions he said, why not?forgot to mention... its a 512B RAM too... vs 64B pic615.

author: Zad
author_rank: Super Contributor
timestamp: August 28, 2010, 04:39:00 pm
content: Prices changes quite a lot from country to country, as the OP is in India, my recommendation would be to get hold of a local electronics magazine and browse the adverts in there.

author: Simon
author_rank: Unknown
timestamp: August 28, 2010, 05:32:06 pm
content: Quote from: shafri on August 28, 2010, 04:00:03 pmwhat does that mean ?perhaps the atmel has an internal 20 MHz oscilator versus the pic having an 8MHz (not 5) internal oscilator and capable of 20 MHz only with an external crystal ?

author: sigxcpu
author_rank: Regular Contributor
timestamp: August 28, 2010, 10:33:05 pm
content: 4cycles per instruction on pic

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: August 28, 2010, 11:26:06 pm
content: For the very low-end apps that these parts are targeted at, CPU speed is rarely an issue - in fact you may often want to run slow to save power - cost and permutation of peripherals is generally the most critical thing.

author: Simon
author_rank: Unknown
timestamp: August 29, 2010, 06:34:35 am
content: Quote from: mikeselectricstuff on August 28, 2010, 11:26:06 pmyea I have an application that I actually have to put a 3.8ms delay into the program loop and thats at 4 MHz

author: abhimanyu
author_rank: Newbie
timestamp: August 29, 2010, 10:11:51 am
content: i know u all are going to kill me after thisit was 512 bytessorryi promise this is not going to happen again

author: Unknown
author_rank: Unknown
timestamp: August 29, 2010, 02:07:55 pm
content: ATtiny85 seems to be the best match in the AVR family. The 512bytes SRAM it the only thing preventing you from moving to a cheaper device like ATtiny25 or 13A. The ATtiny85 (in PDIP or SOIC) is $1.35-1.40 in small quantities (25+) at Mouser or Digikey, something like $2.20 in onsies.I'm sure there are other devices from other manufacturers that would satisfy your specs, there's probably a cheaper PIC option out there, which would work just as well. The parametric product tables or parametric search at Digikey/Mouser are your friends. Just factor in the extra cost for development tools and possibly extra time for studying the different architecture (mainly peripherals as long as you're doing C).