??? 07/20/07 04:37 Read: times |
#142058 - 6800 peripherals on 8052 |
Has anyone tried connecting a 6522 VIA, or any other 6800-bus compatible peripheral to an 8052?
The main difference is the handshaking used; the VIA has /CS, R//W, and the enable clock, E. When E is high a transfer is carried out based on R//W and the other bus signals, it's something akin to /MREQ on a Z80 I suppose. Normally this connects to a clock signal like the 6502 phase 2 clock, though I saw a Z80 design connect it to /IORQ. I'm not sure how to generate these signals. R//W would be the equivalent of /RD and /WR XOR'd together, but to represent the idle state (both strobes high) the peripheral would have to be disabled, probably by gating /CS or E. Then there's the issue of how to derive E itself. I know there are better I/O chips for this purpose that are suited for the 8052, but in this case I need two 8-bit bidirectional I/O ports with the direction controlled on a per-pin basis. The 8255 doesn't quite cut it, but the VIA is perfect. |
Topic | Author | Date |
6800 peripherals on 8052 | 01/01/70 00:00 | |
Some problems | 01/01/70 00:00 | |
What is it about the 6522 that you like? | 01/01/70 00:00 | |
Availability! | 01/01/70 00:00 | |
well ... maybe not so fast, but certainly useable![]() | 01/01/70 00:00 |