PSoC4S System Clocks / Max. CPU Speed

[EmJay]

In PSoC4000S Device-Family there are devices with 48MHz and 24MHz max. CPU speed. The term 'CPU speed' is used in PSoC4000S data sheet and it's not exactly clear to me what this means.

For PSoC4000S devices with max. CPU speed of 24MHz,  which clock is limited to 24MHz?

1. Clock frequency of IMO is max. 24MHz
2. Clock frequency of HFCLK is max. 24 MHz
3. Clock frequency of SYSCLK is max. 24 MHz

If the term 'CPU speed' corresponds to SYSCLK frequency, is it possible to use higher clock frequencies for IMO and HFCLK? For example IMO = 48MHz , HFCLK = 48MHz, SYSCLK = 24MHz

Does the max. CPU speed only restrict CPU core clock or peripheral clocks as well?

[BiBi_1928986 · Accepted solution]

Hello.

The CPU speed is referencing the CPU Core clock, SYSCLK.  So, #3 is correct.

"For example IMO = 48MHz , HFCLK = 48MHz, SYSCLK = 24MHz" is also an allowed configuration (with the following restriction you've mentioned in the next question).

"Does the max. CPU speed only restrict CPU core clock or peripheral clocks as well?" is also correct.  Peripheral  clocks are restricted to the max CPU speed of SYSCLK.  Peripheral clocks are derived from HFCLK and must be equal to or lower than SYSCLK.  So, IMO=48MHz, HFCLK=48MHz, SYSCLK=24MHz, SPI CLK=1MHz would be a valid configuration.

PSoC4000S Architecture reference manual does not answer your questions.  The description is described better in the PSoC4000 (non-S) Architecture reference manual.  And, PSoC4000S Architecture reference manual describes everything as if SYSCLK was at 48MHz.  So, read carefully when using SYSCLK at 24MHz.

I've not tried this (on purpose), but maybe PSoC Creator will flag incorrect clock settings when you configure the clocks.

Good luck with your project.

[EmJay]

Thank you for your helpfull reply. This was exactly what i want to know. 

I did not try PSoC-Creator, but ModusToolbox Device-Configurator V3.10. There it was possible to set all clocks (SYSCLK and peripheral clocks) to 48MHz for my 24MHz CPU speed device.