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Author Topic: 1 bit shift when communicating with SPI using FT4222H  (Read 14143 times)

eomkey

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1 bit shift when communicating with SPI using FT4222H
« on: June 02, 2023, 12:40:02 PM »
Hello,

I am inquiring because there is something wrong with SPI communication using FT4222H.

It works fine at 20Mhz, but if you increase the frequency above, the read data seems to shift by 1 bit.

First, the operation status at 20Mhz.(Sysclk = 80Mhz, DIV = 4)
When I send a command, it responds with 0x2016. Normal operation.
Both the signal waveform and read data are normal.

But it's different at 24Mhz.(Sysclk = 48, DIV = 2)
When I send a command, it responds with 0x100B.
If you look at the signal waveform, it seems to be 0x2016, but in the read data, it reads 0x100B.

I found 0x2016 to be 0x100B if I shift 1 bit right.

I need advice on this phenomenon. Please help me.
Attach the waveform and read data screenshot.
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FTDI Community

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Re: 1 bit shift when communicating with SPI using FT4222H
« Reply #1 on: June 06, 2023, 04:01:43 PM »
Hello,

We assume this is an SPI Master application.
We have already tested this on SPI Flash and it works fine.
Maybe you are encountering some hardware or wiring trouble?
Please make sure the SPI wiring is as short as possible if you want a higher frequency.
Probing the wiring may also cause signal delay so it is not recommended.

Best Regards,
FTDI Community
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