The PIC10F322 has a reset pin named – MCLR – This is PIN RA3 or physical pin 8 on a PDIP device.
This is an optional external input that can reset the device. The pin is active low – meaning bring the pin to ground and it will reset the device.
You also have the option of disabling the MCLR though a configuration word – MCLRE and LVP. Setting both MCLRE and LVP to 0, will disable the MCLR pin and RA3 will function as a normal input pin.
Notice above, I said RA3 will function as a normal input pin. RA3 is not bi-directional like the other pins, it can only be set for input.
What can you do with MCLR.. If you have it enabled as MCLR.
Depending on your circuit, it can be held low until other devices power up.
Put a push button on it and use it as a reset.
Although the datasheet does say that RA3 is connected to VDD (+ voltage) though an internal weak pull-up. I always found it a good idea to supply my own external 10k pull-up resistor.
If you wanted to use a push button reset – tie the 10K pull-up to the pin, and the button to ground. This would be a normally open switch. When you press the button it will complete the circuit to ground, overriding the 10K pull-up and bring MCLR low.
MCLR as Input
For me – I rather have the RA3 pin functional – so I disable MCLR though the configuration word. If you are using XC8 you can include the following config settings to use the MCLR as an input.
#pragma config MCLRE = OFF // MCLR Pin Function Select bit->MCLR pin function is digital input, MCLR internally tied to VDD #pragma config LVP = OFF // Low-Voltage Programming
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