Hi r-type,

That is a great little module ASUS has for their motherboard. The steps you listed for wolfTPM with direct /dev/spi access looks great. Make sure you have the right SPI chip select. The PI has two and they are "/dev/spidev0.0" and "/dev/spidev0.1". The modules Nuvoton provides for the Pi use CS0 (Pin 24).

Also the reset line is active low, so if pulled low it will hold in reset, so make sure it is high. Also you should make sure you have a pull-up on the Chip Select pin to make sure it is only active when the Pi drives it. I would leave the IRQ line alone and not tie to anything. Use 3.3v for VCC.

Thanks,
David Garske, wolfSSL

Hi r-type,

Were you able to get wolfTPM working with the Asus E15028 (Nuvoton NPCT750) on a Pi? Make sure you have the SPI wait state build option enabled `WOLFTPM_CHECK_WAIT_STATE` or use the `./configure --enable-nuvoton` option. Note: I pushed a wolfTPM v2.3 release this week, which does have some Nuvoton Fixups.

Thanks,
David Garske, wolfSSL

On oscilloscope I don't see any signal on MISO line, only on MOSI. Sending init command via spidev_test shows no answer as well:

pi@raspberrypi:~/spi_test/new $ ./spidev_test -D /dev/spidev0.0 -v -s43000000 -p "\x80\xd4\x00\x00\x00"
spi mode: 0x4
bits per word: 8
max speed: 43000000 Hz (43000 kHz)
TX | 80 D4 00 00 00 __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __  |.....|
RX | 00 00 00 00 00 __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __  |.....|

I tested this TPM on ASUS board and BIOS could detect it, so it should be OK. Some connection should be a problem. I tried to set almost all undocumented pins high, but it didn't help. In attachment I push photo of setup with connections as you described.

Hi David,
I also thought last week about too long wires and ordered GPIO Breakout HAT to avoid long wires to breadboard. Unfortunately I still have no reply on MISO. With spidev_test I tried 2 MHz and even 200 kHz, but it didn't help.

pi@raspberrypi:~/spi_test/new $ ./spidev_test -D /dev/spidev0.0 -v -s2000000 -p "\x80\xd4\x00\x00\x00"
spi mode: 0x4
bits per word: 8
max speed: 2000000 Hz (2000 kHz)
TX | 80 D4 00 00 00 __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __  |.....|
RX | 00 00 00 00 00 __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __  |.....|
pi@raspberrypi:~/spi_test/new $ ./spidev_test -D /dev/spidev0.0 -v -s200000 -p "\x80\xd4\x00\x00\x00"
spi mode: 0x4
bits per word: 8
max speed: 200000 Hz (200 kHz)
TX | 80 D4 00 00 00 __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __  |.....|
RX | 00 00 00 00 00 __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __  |.....|