[Bug Report] Spi buffer size has only 8 bit.

[Vlad Mokhnachov]

I have used NRF52840 and SDK 13.0.0. Module SPIM. Library does not support buffer size more then 8 bit. But I try write to register TXD.MAXCNT and I can't write value more, then 255. In datasheet size: 16 bit.

(nrf_spim.h):

__STATIC_INLINE void nrf_spim_tx_buffer_set(NRF_SPIM_Type * p_reg,
                                            uint8_t const * p_buffer,
                                            uint16_t         length)
{
    p_reg->TXD.PTR    = (uint32_t)p_buffer;
    p_reg->TXD.MAXCNT = /*length*/0x0000FFFF;
}

[Jørgen Holmefjord]

Hi,

This feature seems to not be available in the engineering A revison of the nRF52840. I have added a request to change the documentation or add this to the errata document.

The drivers in the SDK is written to support EasyDMA on nRF52832, which is limited to 255 bytes transfers. When this feature is available in the chip, the SDK drivers will be updated to support this.

Best regards,

Jørgen

[Vlad Mokhnachov]

Ok, but problem is not in SDK. Problem is in hardware limitation.

[Jørgen Holmefjord]

Sorry, I misunderstood your initial post. I have updated my answer to avoid confusion.