IO Pi ports
1 Views - Created 03/08/2023
03/08/2023
Posted by:
eddieprice
I am using an IO Pi to control the pwm output from a PIC 12F629 microchip. The 629 has 6 GPIO pins, two are used for the pwm output and the other four are intended to be inputs to control the pwm output. I need a 4-bit port from the IO Pi expander board. Is that possible? I would imagine it means producing some code for the IO Pi. I want to be able to use the "write_port(port,0xXX)" instruction
03/08/2023
Posted by:
andrew
Location:
United Kingdom
Hi
If you wire up the first four pins from the bus on the IO Pi to your PIC micro you can use it as a four bit port with the write_port(port,0xXX) instruction.
The following python code would create an instance of the IOPi object on address 0x20 and set the first four pins to be high.
iobus = IOPi(0x20)
# set port 0 as outputs
iobus.set_port_direction(0, 0x00)
iobus.write_port(0, 0x0f)
If it is easier you can use a binary number instead of hex so you can see which of the pins are being set as high and low. The code below would set pins 1 and 3 as low and 2 and 4 as high.
iobus.write_port(0, 0b00001010)
If you wire up the first four pins from the bus on the IO Pi to your PIC micro you can use it as a four bit port with the write_port(port,0xXX) instruction.
The following python code would create an instance of the IOPi object on address 0x20 and set the first four pins to be high.
iobus = IOPi(0x20)
# set port 0 as outputs
iobus.set_port_direction(0, 0x00)
iobus.write_port(0, 0x0f)
If it is easier you can use a binary number instead of hex so you can see which of the pins are being set as high and low. The code below would set pins 1 and 3 as low and 2 and 4 as high.
iobus.write_port(0, 0b00001010)
04/08/2023
Posted by:
eddieprice
Hi Andrew. Thanks for replying. Unfortunately I have wired the port up as pins 1,3,5,7 as one 4-bit port and pins 2,4,6,8 as the other port. I think I have found a way of doing it. I will set pins 2,4,6,8 to "0" and then output my code on pins 1,3,5,7 and then do the same with pins 1,3,5,7 set to "0" - not very elegant but it should work.
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