can anyone clarify a method towards bulk transfer method from MCU via libopencm3 that exceeds 64 bytes for usb 1.1? I cannot look under the hood of usbd_ep_write_packet and I am not sure whether I can specify a larger byte size that it "auto breaks into chunks" or whether I should pre-chunkify and call that method multiple times
what mcu are you using then I can tell you where the source for the write_packet is. I know it's a bit hard to find because of the indirection
some of the methods are defined in st_usbfs_v1: https://github.com/libopencm3/libopencm3/blob/master/lib/stm32/st_usbfs_v1.c#L30
the file above is the stuff in common between _v1 and _v2 iirc
there is no check or switch statement or whatever that would have clarified
case EXCEEDS_DEVICE_CAPACITY:
maybe the reference manual will clarify how they push the len specifier into what part of a special usb register
it just writes into some register yeah
I think what you want to do to debug this is check the write return value
if it's 0 then the write didn't go though and that's why your host is stuck
(assuming you don't pass in len=0)
we thought we could just simply keep pushing data via the callback
but was that how libopencm intended to support usb transfers
I mean I implemented a working production usb device using this code and I got the code right here :)
there is a part that is interrupt based and has a similar idea to ours:
```static void bulk_tx_cb(usbd_device * usbd_dev, uint8_t ep)
{
char buf[64] attribute ((aligned(4)));
(void)ep;
/* Keep sending packets */
usbd_ep_write_packet(usbd_dev, 0x82, buf, 64);}```
"keep sending packets" <<< evidenced by this
and I read the ST peripheral register docs multiple times over, though I guess mine was _v2 on a STM32F0 instead of _v1 hmm
that has a host side thing too you can play with
haha
one thing though: this thing started because I almost felt like I had 9600bps speeds (worse than serial)