HCS908DV/DZ--TPM--16-bit main counter at 20MHz

[denny_george]

Hello All,

Can the 16-bit main counter of the TPM Module(that can operate as a free-running counter, a modulo counter etc) operate at 20MHz freq?

I will keep Bus Clock=20MHz as a "Clock src and Prescale and Divide select" =1

Message Edited by Geo*** on 2008-09-26 01:42 PM

[UK_CF_FAE]

Hi Nexus,

The answer is Yes, and No....

The max output from the DCO in trimmed mode is 40MHz, and so the max output from the MCG is MCGOUT = 40MHz if the BDIV is set to 0.

The busclk is MCGOUT/2 and so, one of the clock inputs to the TPM module is 20MHz max. If the TPM prescaler bits are cleared  PS[2:0] = 0b000 in the TPMxSC register, then indeed you will get a 20MHz clock source to the timer.

So the answer is Yes.

BUT

do check the latest errata for the device, maskset 3M05C prohibits setting BDIV = 0 in FEI or FEE mode. Maskset errata 1M74K has this errata fixed.

You _may_ be able to purchase maskset 1M74K on a custom part number, but would need to contact the Freescale sales team for your country.

Mark 

[denny_george]

Hi Mark,

Thanks for the valuable inputs regarding maskset 1M74K and 3M05C.

I forgot to tell you I was planning to go for PLL engaged external (PEE) mode.

By varying RDIV,VDIV and BDIV suitably I still can get fBUS=20MHz.Right?

Correct me if I am wrong.

Thanks,