Document the requirement for hardware SPI

I spent a while fighting with my hardware before working this out- if
SPI is disabled in the kernel reads will return all 1s which is very
confusing and looks more like something is wired up wrong when it's
actually correct.
This commit is contained in:
Peter Marheine 2019-02-25 14:56:02 +11:00
parent 13464db5de
commit eb328612b2

View File

@ -16,7 +16,10 @@ The EVT boards can be attached directly to the Raspberry Pi as a "hat". When bu
The only pins that are required are 5V, GND, CRESET, SPI_MOSI, SPI_MISO, SPI_CLK, and SPI_CS.
You can improve performance by attaching SPI_IO2 and SPI_IO3 and running `fomu-flash` in quad/qpi mode by specifying `-t 4` or `-t q`.
The Pi's hardware SPI interface must be enabled in the kernel- use
`raspi-config` or add `dtparam=spi=on` to `/boot/config.txt` and reboot before
using. You can improve performance by attaching SPI_IO2 and SPI_IO3 and running
`fomu-flash` in quad/qpi mode by specifying `-t 4` or `-t q`.
You can get serial interaction by connecting the UART pins, but they are not necessary for flashing.
@ -55,4 +58,4 @@ You can verify the SPI flash was programmed with the `-v` command:
## Checking SPI Flash was Written
You can "peek" at 256 bytes of SPI with `-p [offset]`. This can be used to quickly verify that something was written.
You can "peek" at 256 bytes of SPI with `-p [offset]`. This can be used to quickly verify that something was written.