Sending a buffer over SPI without discarding the result ?

Question

Sending a buffer over SPI without discarding the result ?

max22- opened this issue 8 months ago · 6 comments

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

Answer 1 · 2024-04-29T13:47:53.000Z

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

Answer 2 · 2024-04-30T09:44:56.000Z

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

Answer 3 · 2024-04-30T17:33:22.000Z

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

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Message ID: ***@***.***>

Answer 4 · 2024-04-30T19:42:57.000Z

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/rp2040_big/forth/setup_<type>.fs
as mentioned in the readme.
maybe i've done something wrong ?

Answer 5 · 2024-04-30T19:59:57.000Z

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/rp2040_big/forth/setup_<type>.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/rp2040_big/forth/setup_<type>.fs with: ./utils/codeload3.sh -p <device> -B 115200 serial src/rp2040_big/forth/setup_<type>.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

Answer 6 · 2024-05-03T08:08:40.000Z

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 !