Hello,
I am using the 32kHz output of the MAXIM DS3234 Real-time clock as an external clock input for my PIC16F877A (in place of any oscillator crystal). As I understand the datasheet, the connection should be very simple, and the 32kHz signal should be connected to OSC1/CLKIN of the PIC directly. Similarly, the configuration bits have to be set to one of HS, XT or LP (LP is probably best in this case because of the low frequency, but HS should be great for debugging).
The problem is that it does not work: when programmed, nothing is executed. When in an ICD2 debug session, the session cannot be opened (Error ICD0083). However, everything works when a 20MHz clock is connected externally in the place of the 32kHz. Thus the problem is probably linked to the 32kHz signal.
Upon analysis, the signal appears good enough: there is little noise, its amplitude reaches 0.97 Vcc, and has a duty-cycle of roughly 30-40%. It fluctuates slightly when the ICD2CLK line is active, probably due to the routing, but this should be of little concern.
So if you have any ideas of what I might be doing wrong, please throw suggestions at me! Your help is greatly appreciated!
Franchie.
I am using the 32kHz output of the MAXIM DS3234 Real-time clock as an external clock input for my PIC16F877A (in place of any oscillator crystal). As I understand the datasheet, the connection should be very simple, and the 32kHz signal should be connected to OSC1/CLKIN of the PIC directly. Similarly, the configuration bits have to be set to one of HS, XT or LP (LP is probably best in this case because of the low frequency, but HS should be great for debugging).
The problem is that it does not work: when programmed, nothing is executed. When in an ICD2 debug session, the session cannot be opened (Error ICD0083). However, everything works when a 20MHz clock is connected externally in the place of the 32kHz. Thus the problem is probably linked to the 32kHz signal.
Upon analysis, the signal appears good enough: there is little noise, its amplitude reaches 0.97 Vcc, and has a duty-cycle of roughly 30-40%. It fluctuates slightly when the ICD2CLK line is active, probably due to the routing, but this should be of little concern.
So if you have any ideas of what I might be doing wrong, please throw suggestions at me! Your help is greatly appreciated!
Franchie.
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