This project sounds like a great way for a beginner to get some exposure to PRU programming. I am thinking about giving it a look-see. Does your image come with the source code?
image? you mean picture? The pic provided from Amazon review is misleading, don’t use that. It was an earlier implementation.
how could this description from earlier post be clearer? it is from the actual software (gpio_code.asm). Its’ purpose is to provide symbolic substitution specific to the app (MOSI_HI) to the symbolic substitution in pru.h (pru.h is application agnostic).
is it clearer if I instead specify:
P9_25 ---- sclk
P9_29 ----- mosi
P9_28 — SS/CS
P9_27 ---- DC
P9_31 ----- reset
I didn’t think that was necessary, but am happy to provide it…
If that wasn’t clear, it probably also wasn’t clear that enough of the SPI protocol has been coded into PRU0 to drive the ILI9341 device. (not claiming anything close to complete compliance with SPI). This is a roll your own exercise in SPI communication for one specific device (ILI9341). that is why I specify which pins do what.
If I haven’t answered your question, please restate. Can provide pic if that is what you meant.
That is much clearer. Thank you very much. Wasn’t necessary but, makes is easier on the new user.
My main concern however, was how you did the power supply to the display. I see the BBB can supply up to 250mA on the 3.3V outputs on the P9 header. Did you plug the ILI9341 right into the header? something like:
P9_01 ---- GND
P9_03 — VCC
The ILI9341 datasheet shows that it draws 100uA in standby but, i don’t see what it draws in full on display mode. Just trying to avoid damaging my new hardware before I get to run your awesome clock!!!
This is correct. without a breadboard, you’ll probably want to use two 3.3 sources (P9_03 and P9_04), one for VCC and one for led.
you’ll get plenty of warning if display is underpowered, it will dim on and off. Just be sure to use a 5v supply on the barrel jack, don’t try to power it from the usb connection. (or you can try, just to see it fail)…
I hope that you didn’t pay too much ($15) for one of these… it is good value. I can attest that I tortured these devices for years with misconfigurations, and bad practices without any damage.