LayerscapeのトピックSPI time delay between bytes adjust action consultation

SPI time delay between bytes adjust action consultation

jack_huang1 — Wed, 26 Jun 2024 15:01:08 GMT

Dear;

This project adopts the LS1043A platform and uses SPI interface to communicate with external devices, and meets an SPI problem:
One of the SPI devices has the following requirements for timing, requiring the delay between byte to be less than 400ns, as shown in Figure 1.
The timing diagram is as follows, and the delay between byte is 1us, see Figure 2 for details.

After viewing the code, it is found that because the buffer sent at one time is 24bit (the chip manual requirements), 24 is a multiple of 8 in the code (not a multiple of 16 and 32), so the code is divided into 3 cycles to send 8bit operations in turn, and the delay is brought by separate transmission.
In this case, is there any way to adjust the latency between bytes?
Check the parameter Delay after Transfer Prescaler in the LS1043ARM manual. How do I configure the parameter?

Thank you!

Re: SPI time delay between bytes adjust action consultation

Hector_Villarruel — Thu, 27 Jun 2024 23:05:23 GMT

Hello @jack_huang1

Could you please provide us with more information of which SPI device are you trying to connect?

We will be aware of your kind reply.

BR,

Hector Villarruel.

Re: SPI time delay between bytes adjust action consultation

jack_huang1 — Tue, 02 Jul 2024 03:53:43 GMT

Dear；

The SPI interconnects with the Tranceiver ADI adrv902x. The description of the SPI interface is timely, as shown in the following screenshot. Please check. tINT indicates the delay between Byte and Byte. The maximum value is 400ns. See attachment for SPI description of the device. Thank you!

Best Regards!

Re: SPI time delay between bytes adjust action consultation

Hector_Villarruel — Sat, 06 Jul 2024 00:12:38 GMT

Hello @jack_huang1

Hope this post finds you well,

Based on your last reply, since you are sending 8 bits,

Could you please provide us in how you are doing the SPI communication on the example that you provide us?

We will be aware for your kind reply.

BR,

Hector V

Re: SPI time delay between bytes adjust action consultation

jack_huang1 — Mon, 08 Jul 2024 03:41:54 GMT

Dear；

The spi call procedure is as follows:

As shown above, the bits_per_word field value in the _read_xmit struct is assigned a default value of 8.

What other information do you need? Thank you!

Best Regards!

Re: SPI time delay between bytes adjust action consultation

Hector_Villarruel — Fri, 12 Jul 2024 15:11:29 GMT

Hello @jack_huang1

Hope this post finds you well,

Reviewing your procedure, we notice that you are using SPI dev, which is handled by making transitions defined of 8 bits.

In order to modify this configuration to the 24 bit transitions, you have to modify it on the device tree.

Have a great day.

BR,

Hector Villarruel