ESP8266 Community Forum

- Tue Jun 02, 2015 1:23 pm #19250 I want to connect this module to a 68000 processor. I have neither a UART nor a SPI port, just a parallel port with the address, data and control lines.

What's the cheapest/easiest way of connecting the module to this kind of bus? I had a look to UARTs with parallel interface (such as SC16C550), and I find them a bit pricey (ESP8266 module is cheaper!). I was thinking if there is a better way of connecting it, e.g. using a cheap CPLD (like Xilinx XC2C32) implementing parallel to SPI protocols, to connect to ESP8266 via SPI. Using the CPLD approach has additional advantages (I can add additional peripherals as long as they fit in the CPLD). I thought about using SPI instead of UART because SPI eats a lot less CPLD space.

Can the module be used via SPI? How difficult is it? is there a better/cheaper approach?

- Wed Jun 03, 2015 8:20 am #19333 Moin,

if you don't need much speed you could just use a software serial port like
some people do it when using the arduino as an esp serial terminal.
Just use 2 lines of parallel port. One for input, one for output.

Or do I miss something?

Cal

Get your modules here:

https://www.banggood.com/custlink/KvGGhGF4wG

- Wed Jun 03, 2015 2:50 pm #19369 many microprocessors have hardware SPI I2C and UART pins...your microprocessor according to you doesn't....that means the interface ( SPI I2C or UART ) will have to be coded in software on your microprocessor ( AKA bit banging). You will often find code on the internet for bit banging a specific interface for your microprocessor.

- Sun Jun 07, 2015 5:51 am #19737 Thanks for responses! Unfortunately bit banging is not an option because of the high CPU usage (the microprocessor will be quite busy during communications).

I have been searching SPI and UART cores, and they are too large to fit inside a small CPLD, so unfortunately I will have to go for the hardware UART attached to the microprocessor address/data/control lines.

I might try implementing an even smaller serial/parallel converter on the CPLD to emulate the core functionality of SPI ports... it might fit inside the CPLD and be enough to communicate with the module...