I got a simple loop-back SPI program to work. I connected MISO to MISO with a jumper and then checked to see that the characters I sent out on MOSI matched the ones I got back on MISO.
It appears to be important to to set the slave select high before configuring it as an output or it creates glitches.
MISO is configured with no pullup.
The Nordic has two SPI channels which can be pointed at any set of GPIOs.
p_nrf_spi->PSELSCK = p_spi_master_config->SPI_Pin_SCK;
p_nrf_spi->PSELMOSI = p_spi_master_config->SPI_Pin_MOSI;
p_nrf_spi->PSELMISO = p_spi_master_config->SPI_Pin_MISO;
I initialised the code to run with:
POL=ActiveHigh;
PHA=Leading;
FREQ=125Kb;
BITORDER=MsbFirst
This is right for BusPirate SPI_Sniffer, but the bits are back-to-front on the scope
My program sets up to catch interrupts, and the interrupt handler simply sets a flag when the IO has finished. The main loop
Here’s some output.
0: Hello SPI! => Hello SPI!
1: Hello SPI! => Hello SPI!
2: Hello SPI! => Hello SPI!
3: Hello SPI! => Hello SPI!
4: Hello SPI! => Hello SPI!
5: Hello SPI! => Hello SPI!
6: Hello SPI! => Hello SPI!
7: Hello SPI! => Hello SPI!
8: Hello SPI! => Hello SPI!
9: Hello SPI! => Hel
If the jumper is not in place then the SPI hardware clocks character 255 into the receive buffer.
0: Hello SPI! => ÿÿÿÿÿÿÿÿÿÿ
1: Hello SPI! => ÿÿÿÿÿÿÿÿÿÿ
2: Hello SPI! => ÿÿÿÿÿÿÿÿÿÿ
3: Hello SPI! => ÿÿÿÿÿÿÿÿÿÿ
4: Hello SPI! => ÿÿÿÿÿÿÿÿÿÿ
5: Hello SPI! => ÿÿÿÿÿÿÿÿÿÿ
6: Hello SPI! => ÿÿÿÿÿÿÿÿÿÿ
7: Hello SPI! => ÿÿÿÿÿÿÿÿÿÿ
8: Hello SPI! => ÿÿÿÿÿÿÿÿÿÿ
9: Hello SPI! => ÿÿÿÿÿÿÿÿ
Using the Bus Pirate and SPI_Sniffer
The startup bat file contain this:
SPIsniffer -d COM4 -r 0 -s 125000
pause
The data is interpreted as follows:
BP_record ::= CS_low ‘[‘ { DataPair } CS_hi ‘]’
CS_low ::= 0x5B
CS_hi ::= 0x5D
DataPair ::= MOSI ‘(‘ MISO ‘)’
MOSI ::= .dec .hex
MISO ::= .dec .hex
SPI working on TS06.2
