How can i set spis rx buffer length on nrf52832 SDK13?

RE: How can i set spis rx buffer length on nrf52832 SDK13?

Jørgen Holmefjord — Mon, 29 Jan 2018 08:59:12 GMT

Yes, that is correct.

RE: How can i set spis rx buffer length on nrf52832 SDK13?

freedom118 — Sat, 27 Jan 2018 01:58:33 GMT

Dear Jorgen，

I see. Thanks a lot. so if i want to send or receive a message longer than 255, i need to split and concat the message to packet which max length is 255.

RE: How can i set spis rx buffer length on nrf52832 SDK13?

Jørgen Holmefjord — Thu, 25 Jan 2018 09:59:02 GMT

Hi,

The SPIS peripheral on nRF52832 use EasyDMA to store the received data directly in RAM buffer. EasyDMA have a limit on buffer size of 255 bytes, as seen from the documentation of the RXD.MAXCNT register, which is only 8 bits wide.

In the API documentation of nrf_drv_spis_buffers_set(), the type of the parameter rx_buffer_length is uint8_t, i.e., an 8-bit variable. When you assign 1024 to this variable, it will overflow and you are left with the 8 lower bits of the number (1024 dec = 0100 0000 0000 bin).

Best regards,

Jørgen