To Whom It May Concern,

Hello, is anybody familiar with Philips P89LPC9221 ucontroller?

I am facing problem to calculate the timer overflow of the ucontroller.

I am using the internal RC oscillator with 7.3728MHz. I have set the DIVM = 0x00. Therefore the CCLK should be 7.3728MHz and the PCLK should be 3.6864MHz.

I have set the timer 0 to mode 1 16-bit timer.
MOV TMOD,#00100001B
MOV TAMOD,#00000000B

Now if I wish to create a pulse with frequency = 3.6864MHz/2 by complemeting a port in timer 0 interrupt service routine, what value should i reload the TH0 and TL0?

I have tried to calculate with the following method but using scope to measure the pulse frequency, i always get 50KHz. Is there any mistakes I make?

(65535-x)/3.6564M = 1/3.6564M
65535-x = 1
x = 65534
x = 0xfffe
=> TH0 = 0xff;
TL0 = 0xfe;


Please help. Thanks.

Regards,
IVAN :)