SUB-20 Slave Mode

All about Sub-20 Multi Interface USB Adapter USB to I2C, SPI, GPIO, RS232, RS485, Ir, LCD

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xol
Site Admin
Posts: 241
Joined: Sat Aug 29, 2009 8:04 am

Re: SUB-20 Slave Mode

Post by xol »

OK,
Now I see no excuses ;-)

Can you please run the same test at let's say 100KHz master CLK from DSP.
To my understanding SUB-20 FIFO module is not fast enough to update next byte to be sent and thus it shifts out byte received before.
The 100 KHz (or less) test will show it for sure.

acalogirou
Posts: 11
Joined: Wed Jul 07, 2010 4:06 pm

Re: SUB-20 Slave Mode

Post by acalogirou »

At less than 100Khz it appears to work correctly. How come in that case a read from the SUB-20 app works at more than 100Khz but a write does not? I am taking from all that the max speed i can use the FIFO at is 100Khz.

xol
Site Admin
Posts: 241
Joined: Sat Aug 29, 2009 8:04 am

Re: SUB-20 Slave Mode

Post by xol »

Hi,
Let's increase the speed. Please try 250KHz and 400KHz.

Usually in SPI communication there is a byte to byte delay that is used by FIFO to provide next byte.
Our SPI module is bidirectional. It has double buffer in one direction but not in another. This is the reason I think.

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