OMAP4 McSPI Slave Mode Maximum Clock Rate

Hi Victor,

In master mode supports 48MHz clock as maximum, but for slave mode it should be able to support some more. For more information you can take a look at the TRM from the chip you are using and look for the McSPI Interface.

Hello,

I can't find any specification in the TRM Version K that tells me the maximum clock rate that controller can handle.

Thanks,

Victor

See this section:

23.4.4.2.8 Programmable SPI Clock (mcspim_clk)

There is this table with all supported clock:

Table 23-270. SPI Master Clock Rates

* This is an OMAP4430 TRM Version J

Hello,

This doesn't help since this section is only applicable to Master mode.   The next section is for slave mode.  There is a statement on the fourth line of text on page 4286, " The mcspim_clk frequency of a transfer is controlled by the external SPI master connected to the MCSPI slave device."  So, I guess if the Master can drive the SPI bus at 64MBPS, the McSPI will be able to handle it.

Do you agree?

Thanks,

Victor

Running in slave mode is actually slower than running in master mode. Please check DM (DataManual chapter 6.6.3.1 http://www.ti.com/pdfs/wtbu/OMAP4430_ES2.x_DM_Public_Book_V_D.pdf) for actual numbers, but they seems to be lowered to like 8-16MHz SPI Clock (or maximum 24MHz if certain criterias are fulfilled) => Maximum 8-24Mbps which unfortunately is much lower that the 64MBps originally requested...

I fear you will need to find another path into OMAP for this - Good luck
 Søren

Hello ICe,

I am currently facing the same dilemma described by Victor - I have already performed some initial testing with an external clock of ~36MHz. This does not seem to cause any problems, but following Søren's comment regarding the McSPI Slave limitations documented in the Data Manual 6.6.3.1 I am worried that by exceeding the 24MHz maximum I may run into spurious problems with prolonged usage - my system should be capable of streaming data at close to 48Mbps for long periods (days, months, or more).

Is this, or isn't this possible with the McSPI slave?

Thank you,

Kasper

Kasper,

While it may be possible to overclock the McSPI to 48Mbps, TI can only support clk rates that have been characterized and validated across nominal conditions.   Such operating conditions such as clock jitter, temperature, board layout, etc could influence whether or not >48Mbps-Slave Mode can be achieved.  Therefore, 24Mbps-Slave Mode and 48Mbps-Master Mode is supported.

I recommend using the USB interface if you require >48Mbps.

Marcus

Thank you for your reply Marcus.

Best regards,

Kasper