spectrum
Member
hello all,
i'm posting for some help on missing clock on 16F877A
First of all, i have some questions about the ICSP programming:
I've used ICSP programming algorithm 1, with 13V on MCLR.
Microchip says that this serial programming allow to program the microcontroller in the user circuit application. I've discovered that if there is a crystal resonator connected to osc1/osc2 the configuration bits programming fail, when i read the bits back i get 0x0000. Disconnectiong the crystal seems they are programmed fine, i read them back correctly. So do i have to disconnect the cristal everytime i program the pic ? If so, what is the standard way to go if i have to reprogram many times ?
Once programmed, (conf bits are __CONFIG 0x2F41) there is no way to see the 4Mhz clock signal by the oscilloscope. No signal is generated. I've changed capacitors, nothing change.
I've used 2 capacitors 22pF and crystal configuration.
Is there some particular rules to respect when i build my oscillator on the prototype board ? Do it must stay near the pic, should the ground between 2 capacitors be connected toward some specific pin, instade of a random ground pin ? What are the fisical condition on the board to rispect for a well-done oscillator ?
By the way, i don't remember such difficult thing to get the oscillator running, i suspect there is still some bad programming issue.
Thanks all, every help is appreciated
angelo
i'm posting for some help on missing clock on 16F877A
First of all, i have some questions about the ICSP programming:
I've used ICSP programming algorithm 1, with 13V on MCLR.
Microchip says that this serial programming allow to program the microcontroller in the user circuit application. I've discovered that if there is a crystal resonator connected to osc1/osc2 the configuration bits programming fail, when i read the bits back i get 0x0000. Disconnectiong the crystal seems they are programmed fine, i read them back correctly. So do i have to disconnect the cristal everytime i program the pic ? If so, what is the standard way to go if i have to reprogram many times ?
Once programmed, (conf bits are __CONFIG 0x2F41) there is no way to see the 4Mhz clock signal by the oscilloscope. No signal is generated. I've changed capacitors, nothing change.
I've used 2 capacitors 22pF and crystal configuration.
Is there some particular rules to respect when i build my oscillator on the prototype board ? Do it must stay near the pic, should the ground between 2 capacitors be connected toward some specific pin, instade of a random ground pin ? What are the fisical condition on the board to rispect for a well-done oscillator ?
By the way, i don't remember such difficult thing to get the oscillator running, i suspect there is still some bad programming issue.
Thanks all, every help is appreciated
angelo