what is the minimum switching frequency of PWM in ADuC7026? can i make 40% duty cycle PWM for 150 sec time cycle?
This is explained on page 58 of the REV D data-sheet. For a 41MHz Core clock (CD = 0) with a 16Bit max value for the period you can achieve a 318,75Hz PWM frequency. But the PWM is related to the core clock (CD in POWCON) )and if you run the chip with a CD of 7, which is equal to a 326kHz rather than 41MHz core clock, than the min PWM frequency calulates to 2,49Hz. This is all far away from your 150 seconds. I suggest to use a 1 sec Timer interrupt and than count up the seconds and switch by SW.
What is the application requiring this kind of PWM frequency?
Typical applications use the HW PWM for higher frequencies typical around 10 to 60 kHz for example.
thank you for your reply sir,
Now we use aduc for gas sensor application in that we need very low frequency interms of mHz to Hz range for heater control application. if have any example codes for temperature control please send sir
programming a timer to do a 1 sec interrupt and doing the rest shouldn't be a big task and with a 1 sec tic you can count up a 32-Bit variable as a SW counter - you can count for ~136 years - think your application will not run longer. So i.e. with T2LD = 32768 & T2CON = 0x04C0 you get this 1 second tic and in the interrupt handler you can count up the 32-Bit variable. Based on this variable you can easy generate a more than 1% accurate PWM by switching a GPIO. As a technician or engineer you should be able to do this based on the examples provided by ADI.
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