About eCSPI Master mode Timing Parameters 2.

[takashitakahash]

Hi community.

I previously got a answer by 571220. URL is below.

https://community.freescale.com/message/571220#571220?sr=search&searchId=47af9444-7c49-486b-84fe-ecd...

Would please more information.

Customer intended for use of master mode  eCSPI  of ECSPIx_SCLK = 20MHz (tSW = 25ns) , but in the Master mode
Spec value "ECSPIx_MISO Setup Time (tSmiso)" = 18ns (min) becomes a bottleneck,
The realization of a theoretical point of view has become a difficult situation.

Of course, be affected also the delay on the Slave side, but also

It seems too tight tSmiso = 18 ns (min) values.

Slave mode will be tSmosi = 4 ns (min) is like.

From the data sheet,  it can be read so as to be capable of up to 23.26MHz (tclk = 43ns (min)) as ECSPIx_SCLK at the time of Read, use of this frequency would not have been assumed?

(But in this case slave does not go and does not reduce the output delay of the device in less than 3.5ns, but such a device does not seem to be in reality)

For the "ECSPIx_MISO Setup Time (tSmiso)",  would you have any acceptable value as ability?
Therefore, even in the talent, set-up time of i.MX has not be satisfied 17.5ns (i.MX setup time specified min 18ns).

Would you please see attachment Fig.
  Thanks,

Best.  T.Takahashi

[Yuri · Accepted solution]

Hello,

   I am afraid, that for mentioned in Your considerations SPI slave device with

"SCLK Fall to MISO Propagation Delay" of 14.2 ns, the only solution to use it

(reliably) is SPI frequency decreasing.

Have a great day,
Yuri

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