GARTHWILSON wrote:
I'm not sure what you mean by "configuration register,"
I want to use that register to determine certain system settings.
At Startup I want to configure port A of VIA1 as output. The bits 0-5 are connected to an AVR. The AVR scans those bits continuously.
Attachment:
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The AVR is also connected to the Flash memory’s A14, A15 and A16. Which selects the ROM bank.
Bit 3 enables or prohibits writing to flash. I added also a jumper as you suggested. Bit 4 and 5 determines the clock speed which is provided by the AVR. It will give the following frequencies:
Code:
00 14,7456
01 7,3728
10 3,6864
11 1,8432
They go through a 74AC74 and the system can run on those frequencies, divided by two:
Code:
00 7,3728
01 3,6864
10 1,8432
11 0,9216
According to your RS-232 primer, the 6551 could accommodate a baud rate of 115200 with a PHI2 of 7,3728 MHz.
In the meanwhile, before I get my WDC parts, I’m going to make a simplified version on PCB. Just for practicing. I need a simpler version, the PCB gets too crowded.
BigEd wrote:
The idea that others are likely to hit the same problem is, think, far-fetched.
so I could leave them unconnected without harm. But I’ll read those topics anyway.