I/O chip with at least 52 I/O pins? - Page 1
Forum section: electronics / projects

author: Kryoclasm
author_rank: Regular Contributor
timestamp: April 10, 2014, 05:24:52 am
content: Does anyone know if such a thing exists?My goal is to make a small device that accepts an input on one of 26 pins and routes it to one of 26 different output pins.I would like to either do a one time program and have it nonvolatile...or lacking that, an on the fly program on each boot up.I don't know much about FPGA's, so I am not sure if that where one should start.

author: Smokey
author_rank: Super Contributor
timestamp: April 10, 2014, 05:49:13 am
content: What kind of input? Analog or all digital? How fast? How much prop delay can you deal with?For digital a CPLD might be a good option. Xilinx XC9500 or coolrunner maybe.

author: poorchava
author_rank: Super Contributor
timestamp: April 10, 2014, 06:10:31 am
content: CPLD

author: mariush
author_rank: Super Contributor
timestamp: April 10, 2014, 06:13:34 am
content: Any PIC / AVR with at least 28 io pins and a bunch of shift registers, or a microcontroller with 52 io pins or more... but as Smokey says... it depends on what inputs you have.For example something that should work :http://www.digikey.com/product-detail/en/PIC16F1526-I%2FPT/PIC16F1526-I%2FPT-ND/2651377http://www.digikey.com/product-detail/en/PIC16LF1526-I%2FPT/PIC16LF1526-I%2FPT-ND/2601497

author: Kryoclasm
author_rank: Regular Contributor
timestamp: April 10, 2014, 02:23:10 pm
content: Well technically the inputs would be digital.The idea is to make a solid state alpha shift cypher...abcdefg = oejpsczSo, just apply power to the chip, then put a voltage at one of the alpha inputs like "G" and then I would get an output voltage at out put "Z"This whole thing is for making an electro-mechanical enciphering machine, with plugin cards that change the encryption.I can be done with a rats nest wire system, but I want it to be flat and programmable.

author: miguelvp
author_rank: Super Contributor
timestamp: April 10, 2014, 08:21:07 pm
content: My new favorite mcu manufacturer:http://www.cypress.com/?docID=47570Versatile I/O system28 to 72 I/Os (62 GPIOs, 8 SIOs, 2 USBIOs)Any GPIO to any digital or analog peripheral routabilityLCD direct drive from any GPIO, up to 46×16 segmentsCapSense® support from any GPIO1.2 V to 5.5 V I/O interface voltages, up to 4 domainsMaskable, independent IRQ on any pin or portSchmitt-trigger transistor-transistor logic (TTL) inputsAll GPIOs configurable as open drain high/low, pull-up/pull-down, High-Z, or strong outputConfigurable GPIO pin state at power-on reset (POR)25 mA sink on SIOPage 114 to check for the actual chip that will suit your needs.cheapest I can find around $13:http://www.futureelectronics.com/en/technologies/semiconductors/microcontrollers/32-bit/Pages/7028727-CY8C5868AXI-LP032.aspx?IM=0Edit: this is a 32-bit ARM Cortex-M3 with programmable digital and analog circuitry, think about it as in CPU meets CPLD.

author: Q-Kernel
author_rank: Contributor
timestamp: April 10, 2014, 08:55:39 pm
content: Quote from: miguelvp on April 10, 2014, 08:21:07 pmThe Cypress PSOC is a very powerful MCU but expensive. The PIC24FJ128GC010 ($5.50 single quantities) is a bit slower but has similar powerful peripherals:- 4 channel delta sigma ADC- 50 channel 10M samples/second pipelined ADC- 2 DAC's- 2 opamps- 3 comparators- 3 voltage refrence- 9 channel Input Capture- 9 channel Output Compare (PWM)- 2 channel I2C- 2 channel SPI- 4 channel UART- External memory bus- LCD controller- USB on the go- 80 IO pins with Peripheral pin select- Low power (18nA deep sleep mode)- 6 DMA channels- >70 interrupt vectors- 128kB Flash- 8kB RamThere is a trend to put more and more stuff in the MCU which is great.

author: nctnico
author_rank: Super Contributor
timestamp: April 10, 2014, 11:01:31 pm
content: Quote from: Kryoclasm on April 10, 2014, 05:24:52 amUse a string of shift registers like the HC595 (output) and HC165 (input). Like:http://s.eeweb.com/members/eugene_lisovy/answers/1366650524-SPI_74HC595_74HC165.pngA small microcontroller like a MSP430 in a SOIC8 package can run the system.

author: Someone
author_rank: Super Contributor
timestamp: April 10, 2014, 11:10:09 pm
content: Quote from: Kryoclasm on April 10, 2014, 02:23:10 pmIn the digital world this is described as one-hot coding, you can encode that signal to a binary address/index with a priority encoder (they chain/stack to make larger encodings) which will make the cypher/translation/transform much easier to program and then decode it back to one-hot.One-hot -> 74HC148 -> Binary -> ROM -> Binary -> 74HC138 -> One-hot

author: nctnico
author_rank: Super Contributor
timestamp: April 10, 2014, 11:52:53 pm
content: Such a solution would suffer from glitches. I'd add input and output registers (flipflops) which are clocked from a simple oscillator.

author: Kryoclasm
author_rank: Regular Contributor
timestamp: April 11, 2014, 01:20:26 am
content: Quote from: Someone on April 10, 2014, 11:10:09 pmThis looks like something I will peruse, Thanks for the ideas guys!