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Re: Writing to NIC at IO3-7 always writes a 9F. Read works fine.
Posted: Fri Jan 10, 2025 12:04 pm
by gz0000
theory wrote: ↑Fri Apr 19, 2024 3:23 am
Hello everyone,
I've been working on a 10/100 NIC for a few weeks now and I almost have it working. For some reason though when I try to write to the card at IO3 ($9f61) or any other IO address, it always writes a $9f to the device. The chip that I am using for the ethernet controller is the Wiznet W5100S. Looking at the timing diagrams of the W5100S and the 65C02 everything appears to be OK even at 8MHz. While I was fairly confident that I was meeting timing requirements I still even tried ANDing the CS with the clock but still the same results; reads just fine but always writes a 9f. I feel like I'm missing something here, which is very possible as I'm fairly new to 65C02 assembly and building hardware for it. I can provide a schematic of the IO select and R/W logic if need be.
The picture below shows the CS (Yellow) WR# (Pink) and D0 (Blue). As you can see, bit 0 is set when the CS and WR signals go low ($9f).
Apologies if this is a newb mistake. Any help would be most appreciated.
Thank you.
Hello!
Did you manage to establish robust communication between 65C02 and W5100S?
Could you share your latest findings?
I my similar project I used 74LS139 for R/W decoder, but communication between 6502 and W5100S was not robust.
I also tried with shorter !W signal (using 74HCT123), whereas !R signal was sinchronised with Phi2 using 74LS00. This way writting to W5100S was OK, but reading was still not stable.
Re: Writing to NIC at IO3-7 always writes a 9F. Read works fine.
Posted: Fri Jan 10, 2025 12:09 pm
by gz0000
theory wrote: ↑Fri Apr 19, 2024 3:23 am
Hello everyone,
I've been working on a 10/100 NIC for a few weeks now and I almost have it working. For some reason though when I try to write to the card at IO3 ($9f61) or any other IO address, it always writes a $9f to the device. The chip that I am using for the ethernet controller is the Wiznet W5100S. Looking at the timing diagrams of the W5100S and the 65C02 everything appears to be OK even at 8MHz. While I was fairly confident that I was meeting timing requirements I still even tried ANDing the CS with the clock but still the same results; reads just fine but always writes a 9f. I feel like I'm missing something here, which is very possible as I'm fairly new to 65C02 assembly and building hardware for it. I can provide a schematic of the IO select and R/W logic if need be.
The picture below shows the CS (Yellow) WR# (Pink) and D0 (Blue). As you can see, bit 0 is set when the CS and WR signals go low ($9f).
Apologies if this is a newb mistake. Any help would be most appreciated.
Thank you.
Hello!
Did you manage to establish robust communication between 65C02 and W5100S?
Could you share your latest findings?
I my similar project I used 74LS139 for R/W decoder, but communication between 6502 and W5100S was not robust.
I also tried with shorter !W signal (using 74HCT123), whereas !R signal was sinchronised with Phi2 using 74LS00. This way writting to W5100S was OK, but reading was still not stable.