2 wire SPI

[Markus]

Dear experts,

I'm using a 16LF877A to interface a GLCD with a built-in controller. Unfortunately the display uses some weird sort of SPI hardware. The MOSI and MISO lines are tied together. I connected this line to the PIC's SDO pin. Result: I'm able to write data but I can't generate the clock and read the data from the display 'by hand' (although I set the TRIS register correctly depending on read/write).
So, what are your suggestions? Get rid of the MSSP and communicate with the LCD via normal digital pins (software SPI)?

Markus

[rnielsen]

Do you have a manufacturer/model# or specifications for the display? It might help to see what it's communication specifications are before replying with any advice.

Ronald

[valemike]

I've done two-wired signaling for a vacuum fluorescent display, and it was a nonstandard scheme. I pretty much just had to designate my two pins as digital i/o and bitbang away.

I havent done much SPI in my life, but i don't think a 2-wired spi exists. Perhaps you are really seeing an "I2C" diagram, but the lcd manufacturer doesn't want to call it "i2c" because it is trademarked?

[Guest]

The Dallas DS1302 Timekeeping Chip is a 3-wire "SPI": /CS (chip select), CLK (clock), and I/O (data input/output). The I/O line is bidirectional. In the data sheet they call it "synchronous serial communication," not SPI.

I believe the term "SPI" is trademarked.

Gotta bang those bits by hand I think. Its more fun this way anyway.....

Mike

[Markus]

First of all, I made it work by using a mixture of bitbang and the built-in MSSP module.