AVR Freaks

making it work is already an achievement

Well, I started with an example I found online written in 2015, and nothing appears newer that does better.  But that person also was crippled by having to make guesses about what to do.  Other sources discussing parallel interface mention bugs or inconsistencies in it operation.

One thing that I found is that I can only tell the CH386 to expect up to 127 bytes.  An 8 bit value is passed so it OUGHT to be able to accept up to 255, but this does not seem to work.  The code that works with a 127 byte transfer fails with even one more byte.  And it seems as if it might have been intended to be able to tell it a 16 bit value of bytes to expect in the transfer because there is another byte (always 0x00) that follows the first, functional, byte.  And the datasheet seems to indicate that it expects a 16 bit value.  Appears to be a bug with how the serial interface works on the chip.

I would consider the parallel or SPI interface to the CH376, but for this particular application I need to have as few pins as possible.  I am using it on a M328 (Arduino), and I am already using 16 pins for an external device interface (8 parallel data pins, and 8 other handshaking/signaling pins.  So, I am running out! 

I may end up piggybacking the CH376 onto the hardware serial pins, shared with the USB chip for programming the Arduino).  That would free up 2 pins used for software driven serial.

I just can't see how this CH376 chip can be a commercial success.  Over many years, there are no resources on the 'net  demonstrating a fully functional interface.  I can only see "examples" that are partially non-functional.  Once I get this project working well then I will post it to github.

I am still keeping my eyes and ears open for examples of fully functional CH376 serial interfacing.

-Tony