topic Re: qe32 - ics in 8-bit Microcontrollers

qe32 - ics

roberto_m — Tue, 13 Dec 2011 01:33:31 GMT

hi, I'm setting up qe32 clock. It is very difficult.

I have an external crystal wit 32768 kHz.

I need a 39.85 MHz DCOoutput and f_bus about 20 MHz.

I also use rtc => 2 s. interrupt. ( RTCSC = 0x65; RTCMOD = 0x03

Actually I use this procedure to setup the ICS:

   /* ICSC1: CLKS=0,RDIV=0,IREFS=0,IRCLKEN=1,IREFSTEN=1 */
setReg8(ICSC1, 0x03);                /* Initialization of the ICS control register 1 */
/* ICSC2: BDIV=0,RANGE=0,HGO=0,LP=0,EREFS=1,ERCLKEN=1,EREFSTEN=0 */
setReg8(ICSC2, 0x06);                /* Initialization of the ICS control register 2 */
while(!ICSSC_OSCINIT) {              /* Wait until the initialization of the external crystal oscillator is completed */
}
/* ICSSC: DRST_DRS=1,DMX32=1 */
clrSetReg8Bits(ICSSC, 0x80, 0x60);   /* Initialization of the ICS status and control */
while((ICSSC & 0xC0) != 0x40) {      /* Wait until the FLL switches to Mid range DCO mode */
}

If i am connect with bdm and I go in stopmode3, after resume I have a correct clock. If I disconnect the bdm, clock changes. Why? Where I am wrong?

Thank you.

Roberto.

Re: qe32 - ics

bigmac — Tue, 13 Dec 2011 09:34:14 GMT

Hello Roberto,

How do you ascertain that the bus frequency has altered when you remove the Multilink? The bus frequency cannot be determined from the RTC module, since this makes use of the internal reference source.

It would be expected that the internal reference frequency will differ between BDM and normal operating mode. But this would not affect the bus frequency for FEE mode. An excerpt from the Reference manual:

ICS Trim Register (ICSTRM)

Note: TRIM is loaded during reset from a factory programmed location when not in BDM mode. If in a BDM

mode, a default value of 0x80 is loaded.

Regards,

Mac

Re: qe32 - ics

roberto_m — Tue, 13 Dec 2011 15:55:26 GMT

Hi Bigmac.

I'm using a TPM module, and tpm overflow to genrate a clock on a pin (bus clock is the clock source for tpm, in my case). I made some calculus and set an appropriate "modulo". When I am in bdm mode the clock works as I expected. If I am not in bdm mode it doesn't work as I expected.

Roberto

Re: qe32 - ics

roberto_m — Tue, 13 Dec 2011 17:44:12 GMT

If I use an external crystal as reference, why I have to set up the trim?

Thank you.

Re: qe32 - ics

roberto_m — Tue, 13 Dec 2011 21:39:46 GMT

Solved.

I forget to set EREFSTEN = 1. If this option is set, crystal, keeps going on, after mcu enters in stop mode.

Thank you bigmac.

Roberto