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| Not being able to test 82c55a |
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| gkmaia:
Having a hard time to test a 82c55a. I am following the truth table but I can only send data from the ports to the data bus. And not being able to send the data from data bus to ports. I am attaching A0,A1,CS,RD & WR directly to gnd OR VCC as required by the table and sending 5v pkpk signals from and to ports/bus. What am I missing here? |
| MK14:
What about the RESET pin ? |
| DrG:
--- Quote from: gkmaia on August 02, 2020, 09:39:36 pm ---Having a hard time to test a 82c55a. I am following the truth table but I can only send data from the ports to the data bus. And not being able to send the data from data bus to ports. I am attaching A0,A1,CS,RD & WR directly to gnd OR VCC as required by the table and sending 5v pkpk signals from and to ports/bus. What am I missing here? --- End quote --- Have you reviewed the modes and set them as you intended and using the correct ports for the mode? https://ekoharsono.files.wordpress.com/2012/10/5-82c55-programmable-peripheral-interface1.pdf? [*dayam* I have not thought about that chip in many years.] |
| gkmaia:
Yes. I am using it as Mode 0 port A B or C. CS A0 and A1 LOW. I am not going down A0 and A1 HIGH and using the control register. Just basic data to and from ports flow. RESET pin is LOW. But it actually does not make a difference when I change it. |
| DrG:
circuit? code? |
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