Sending a buffer over SPI without discarding the result ?

[max22-]

Hi, i am trying to port some C code to forth, to read some data from a MCP3008 digital to analog converter. i need to send 3 bytes, and receive 3. i managed to do it using >spi and spi>, but is there any faster way to do it ? unfortunately buffer>spi discards the result, and spi>buffer uses a constant filler byte (i need to send 3 different bytes). thanks Maxime

[tabemann]

Are you using the RP2040? Because if you are there is the word buffer>spi-raw-dma ( buffer bytes dma1 dma0 spi -- last-data ). Note that for this word you need to provide your own DMA channels (which can be dynamically allocated with dma-pool::allocate-dma), and it only reports back the last unit of data received.

Travis

[max22-]

Unfortunately i need the last 2 bytes of data :(

i think in the release this word is not present, if i am right ? i've cloned the repo and built it from source, to try this word, but when i send setup_full_usb.fs i get this error : \ Iterate executing an xt over a byte array : citer ( ??? addr count xt -- ??? ) ( xt: ??? c -- ??? ) { xt } over + { addr end-addr } begin addr end-addr u< while addr c@ xt execute 1 +to addr repeat unable to parse: addr at Line 70 in File ./src/common/forth/lambda.fs

[tabemann]

On Tue, Apr 30, 2024 at 4:45 AM Maxime ANDRÉ @.***> wrote:

Unfortunately i need the last 2 bytes of data :(

Then you are pretty much stuck with >SPI SPI> unless you write a custom word for this purpose.

i think in the release this word is not present, if i am right ?

Correct, there is currently no built-in word for retrieving the last two units of data received while sending data; note that one can receive the last 16 bits of data, but only if one is in 16-bit mode.

i've cloned the repo and built it from source, to try this word, but when i send setup_full_usb.fs i get this error : \ Iterate executing an xt over a byte array : citer ( ??? addr count xt -- ??? ) ( xt: ??? c -- ??? ) { xt } over + { addr end-addr } begin addr end-addr u< while addr c@ xt execute 1 +to addr repeat unable to parse: addr at Line 70 in File ./src/common/forth/lambda.fs

How are you doing this exactly, because I have never run into this issue?

Travis

Message ID: @.***>

[max22-]

ok thank you !

for the error, i have run "make", copied the uf2 on the board (a xiao rp2040), then with e4thcom i've run `

include src/rp2040big/forth/setup.fs

` as mentioned in the readme. maybe i've done something wrong ?

[tabemann]

On Tue, Apr 30, 2024 at 2:43 PM Maxime ANDRÉ @.***> wrote:

ok thank you !

for the error, i have run "make", copied the uf2 on the board (a xiao rp2040), then with e4thcom i've run

include src/rp2040big/forth/setup.fs

as mentioned in the readme. maybe i've done something wrong ?

Which UF2 did you copy onto the board? For this it needs to be an 'rp2040_big' 'kernel' UF2 file.

Also, I recommend you load src/rp2040big/forth/setup.fs with:

./utils/codeload3.sh -p -B 115200 serial src/rp2040big/forth/setup.fs

This is what my build scripts use, and I have not had a problem with it (and it is specially implemented to handle the RP2040 rebooting mid-upload, which is necessary for building zeptoforth from source).

Travis

[max22-]

ok now this time it works ! i'll try look at the code to see if i can create a new word that suits to my needs ! thanks !