Is this SPI speed set from the Raspberry Pi SPI read block correct?

When using the SPI read block (2017b, rpi3b) - I believe the SPI bus speed setting in the generated code is incorrect, can anyone confirm?

I set the spi speed under configuration parameters -> hardware implementation -> target hardware resources -> SPI to 16000kHz but the generated c code file it is still hard coded to 500kHz.

Is there a way to edit the c file and recompile to test?

/* Start for MATLABSystem: '<Root>/SPI Register Read' */
95      untitled_DW.obj.isInitialized = 0;
96      obj = &untitled_DW.obj;
97      untitled_DW.obj.isInitialized = 1;
98      SSPinNameLoc = SPI0_CE1;
99      MOSIPinLoc = MW_UNDEFINED_VALUE;
100      MISOPinLoc = MW_UNDEFINED_VALUE;
101      SCKPinLoc = MW_UNDEFINED_VALUE;
102      obj->MW_SPI_HANDLE = MW_SPI_Open(0U, MOSIPinLoc, MISOPinLoc, SCKPinLoc,
103        SSPinNameLoc, true, 0U);
104      MW_SPI_SetBusSpeed(untitled_DW.obj.MW_SPI_HANDLE, 500000U);

[Myles Joseph]

It appears so because when I remake the file

sudo -f filename.mk

after changing the value from 500000 to 16000000 I start to see data as expected.

you can execute the made package by running

sudo ./filename.elf

(in the folder above)

there also seems to be some changes not made in the MW_SPI.c file as well to reflect the proper speed.

I would also like to note that to those looking to transfer a large amount of bytes (over 4096) the SPI file also seems to be modifying the output to zeros. I believe this is due to the receive buffer size that is expected on the raspberry pi. It may be the pi settings, or the generated code limiting it.

Answer 1

[Myles Joseph]

I have confirmed that if there are more than 4096 bytes requested by the block, it will return nothing. To receive a larger message via SPI, you must

1. generate code to raspberry pi
2. go to the folder where the files are made on rpi
3. open up MW_SPI.c
4. remove

if (DataLength > 4096) {
     return MW_SPI........
}

5. it may be necessary to also increase the spi buffer size on the pi

/* modify /boot/cmdline.txt to include spidev.bufsiz=131072 */