mstechca
New Member
I made myself a rather basic circuit using Atmel's AT89C2051 IC.
Basically all it does is detect that the chip is valid and then proceeds to run the code.
Once I insert the microcontroller (or uC for short) into the socket, it appears to be properly detected by the circuit, BUT once I reset the uC, the circuit does not work. When I checked the outputs of each pin P1.0 through P1.7 they were all 1's. Probably because they were at an impedant state, and I used pull-up resistors (1K) to make each pin a logic high by default.
I am a bit confused with Atmel's documentation because:
1. It states that when Pins P3.3 through P3.7 are all logic 0 (which I set them to), and Pin P3.2 is logic 1 (also set), and the reset pin is high, the first thing that is output on the P1 pins is the binary code 00011110, because that is part of the uC's signature. This is what I want to happen on every reset.
2. It states that as soon as I make reset logic 1 from the logic 0 state, P1's output will be all logic 1's.
So what I am asking is, How do I make the uC output the signature (as described above), every time I reset it without having to remove and then reinsert the uC?
Basically all it does is detect that the chip is valid and then proceeds to run the code.
Once I insert the microcontroller (or uC for short) into the socket, it appears to be properly detected by the circuit, BUT once I reset the uC, the circuit does not work. When I checked the outputs of each pin P1.0 through P1.7 they were all 1's. Probably because they were at an impedant state, and I used pull-up resistors (1K) to make each pin a logic high by default.
I am a bit confused with Atmel's documentation because:
1. It states that when Pins P3.3 through P3.7 are all logic 0 (which I set them to), and Pin P3.2 is logic 1 (also set), and the reset pin is high, the first thing that is output on the P1 pins is the binary code 00011110, because that is part of the uC's signature. This is what I want to happen on every reset.
2. It states that as soon as I make reset logic 1 from the logic 0 state, P1's output will be all logic 1's.
So what I am asking is, How do I make the uC output the signature (as described above), every time I reset it without having to remove and then reinsert the uC?
