I have an Olimex LPC2148 board with the ALFATxp firmware, which works fine with a UART interface.
I have been trying to get this working with the SPI interface using a Xilinx FPGA providing the SPI link.
The board has been set with I2C_SEL = 0 and SPI_SSEL = 1. The SPI clockrate is only around 400KHz.
I am monitoring the SPI signals with a logic analyser but have not seen any action on the MISO line, not even garbage. The clock, chip select and MOSI lines toggle fine.
The MISO line does sometimes go high on bootup so I don’t think there is any short on it. The line at the moment only goes to one of the logic analyser pins.
I have read the thread DOSonCHIP – Example code for SPI interface which applies more to the uALFAT. It does agree with what I am doing.
I must be doing something wrong so any ideas would be welcome
I have a logic analyser on the SPI pins from FPGA to LPC2148, so I can monitor the system. Also I checked with a scope just in case the analyser was somehow faulty
The MISO line is currently not connected to the FPGA only the analyser as I suspected initially a short somewhere.
The problem with the SPI communication was a mistake in the ALFATxp
manual where the jumper settings for the different communication modes are described (page 11, section 4.1).
The manual has now been corrected and a note to this effect was posted in the GHI Electronics forum. I am assured that the SPI mode now works (I think it always did but not with the settings as described in the manual). I have not yet had time to test this mode myself.