Hello, I'm programming in mode 0 a 82c55 with a z80 to read and burn an eeprom.
So I have set one port to read the EEprom data as input, and two ports as output for the addresses.
I put the address on the output with the Z80, than try to read the eeprom with the z80 and store the data in the A register.
But it doesn't work...In the istant i read the data, the outputs port for the address go to an high status.....
Question: is it possible to write two output ports, and then read with the third port just after that?
When I read, the two ouputs shouldn't be latched and maintain the address while I read the data?
If I read from a port, data are maintained on the other two output ports in the same time?
I succeded to burn the eeprom but in this case all the 3 ports were outputs....I cannot verify what I have just written since I cannot read while I out the adresses........
my program:
set 8255 as output,output,read;
set via z80 a 16 bit address word and put on the two ports output;
outputs stay latched while Z80 reads the data with the third port
this program is simple but doesn't work...
....please help!
So I have set one port to read the EEprom data as input, and two ports as output for the addresses.
I put the address on the output with the Z80, than try to read the eeprom with the z80 and store the data in the A register.
But it doesn't work...In the istant i read the data, the outputs port for the address go to an high status.....
Question: is it possible to write two output ports, and then read with the third port just after that?
When I read, the two ouputs shouldn't be latched and maintain the address while I read the data?
If I read from a port, data are maintained on the other two output ports in the same time?
I succeded to burn the eeprom but in this case all the 3 ports were outputs....I cannot verify what I have just written since I cannot read while I out the adresses........
my program:
set 8255 as output,output,read;
set via z80 a 16 bit address word and put on the two ports output;
outputs stay latched while Z80 reads the data with the third port
this program is simple but doesn't work...
....please help!