I've used a few PicAxes before, so have some experience, but am stumped here.
I have a 28X2, with the prescribed serial download circuit (22K series, 10K from rs232 input to gnd) on the 28X2's RxD signal (pin6) which is connected to a PC's COM1: port tx-data, and the 28X2's TxD (pin7) having a direct output to same COM1: serial port's rx-data.
The PC's port has rs232 voltages on it, as expected.
When I tell the Editor to program the 28X2, I see the PC's tx-data line go from low (-10v) to high (+10v) for 5 seconds, then it appears the Editor gives up and I get the failure dialog.
When the PC's tx-data line is high during the 5s interval, the 28X2's RxD pin is still low (at gnd), so the high from the PC is not causing the 28x2's RxD pin to go high. This clearly means there's a problem, as this 'wake-up' signal from the PC isn't registering to the 28x2. I've checked the 22k series resistor and it's good (ie, not open).
Power, Gnd and Reset* on the 28x2 are good (+5v, 0v, +5v)....
I have an external 8mhz resonator, and curiously I see a 2ms burst of 8mhz oscillation there, every 35ms. Not sure what's going on there, but I think it doesn't matter as coming out of reset, I think the 28x2 is running on the internal 8mhz RC-oscillator.... maybe this is a clue to somebody smarter than me though.... does it possibly mean that the 28x2 is going thru some kind of reset oscillation?
These are fresh-out-of-the-box 28x2's.
Really stumped on this - appreciate ANY ideas.
-mark
I have a 28X2, with the prescribed serial download circuit (22K series, 10K from rs232 input to gnd) on the 28X2's RxD signal (pin6) which is connected to a PC's COM1: port tx-data, and the 28X2's TxD (pin7) having a direct output to same COM1: serial port's rx-data.
The PC's port has rs232 voltages on it, as expected.
When I tell the Editor to program the 28X2, I see the PC's tx-data line go from low (-10v) to high (+10v) for 5 seconds, then it appears the Editor gives up and I get the failure dialog.
When the PC's tx-data line is high during the 5s interval, the 28X2's RxD pin is still low (at gnd), so the high from the PC is not causing the 28x2's RxD pin to go high. This clearly means there's a problem, as this 'wake-up' signal from the PC isn't registering to the 28x2. I've checked the 22k series resistor and it's good (ie, not open).
Power, Gnd and Reset* on the 28x2 are good (+5v, 0v, +5v)....
I have an external 8mhz resonator, and curiously I see a 2ms burst of 8mhz oscillation there, every 35ms. Not sure what's going on there, but I think it doesn't matter as coming out of reset, I think the 28x2 is running on the internal 8mhz RC-oscillator.... maybe this is a clue to somebody smarter than me though.... does it possibly mean that the 28x2 is going thru some kind of reset oscillation?
These are fresh-out-of-the-box 28x2's.
Really stumped on this - appreciate ANY ideas.
-mark
