SPI read, write and command

Tue 2021.03.09

Hi @Ruprect99 Rob, I do not have that hardware to test, but a few ideas do come to mind:

'but info is just full of zeros.'

If the commands going out are correct, it sounds like they aren't received, so no data transfer occurs. Is it possible MISO and MOSI are wired backwards?

https://en.wikipedia.org/wiki/Serial_Peripheral_Interface

This was a fundamental struggle I had, with my first experience with SPI. Your snippets do not show how SPI is setup, so I'd first double check to make sure the code definitions match the actual wiring. Also, make sure of a solid ground between the uP, the e-Ink display and the power supply.

Has an attempt been made to mirror the code shown in another e-Ink example:

https://www.espruino.com/SSD1606

Using the available SPI functions:

http://www.espruino.com/Reference#SPI
http://www.espruino.com/SPI

The snippets shown in post #1 don't quite mirror the SSD1606 e-Ink example. I had a similar experience and the community helped with SPI examples and snippets:

Have you tried hard coding the register values in place of the constants, to verify that the constants are as they should be. e.g. 32bit vs 16bit, actual hex value and not a string representation, etc.

Examples snippets

http://forum.espruino.com/conversations/336724/#comment14838658

For what it's worth, after hours of struggle with SPI, I2C and UARTS, I eventually buckled and picked up a logic analyzer ~$20 that provides immediate feedback on what is on the data lines. I had a floating CS chip Select that rounded out the leading edge, so the receiving device never started the data receive, and thus nothing during the expected read was seen. Here are some sample images, but with a UART:

JPG Images

http://forum.espruino.com/comments/14687689/

Note the protocol analyzer output that allows the conversion of Hi-Lo to actual ASCII we may read

Here is a full example by @urish, follow the gist link:

http://forum.espruino.com/comments/14303452/