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| SE/30 Real Time Clock Chip |
Posted by: bdurbrow on 2021-07-23 05:14:39
I'm absolutely positive that this has been posted before; but both the site search and google are not turning it up.
Somebody had extracted or reverse engineered the code for the SE/30's RTC, and posted it somewhere.
Anybody remember where??? |
Posted by: cheesestraws on 2021-07-23 05:23:42
Someone built a replacement PRAM chip based on a little Atmel chip, is that what you're thinking of?
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Posted by: bdurbrow on 2021-07-23 05:37:36
I was pretty sure it was a PIC that their code ran on, but if it's got the requisite protocol laid out, I could start from there and cook up something suitable... |
Posted by: cheesestraws on 2021-07-23 05:41:17
Hmmmm, I don't think I've heard about a PIC one if so, only an AVR. Are you thinking of the ADB chip? That's a PIC on the original boards, and the code for that is definitely floating about. |
Posted by: robin-fo on 2022-04-12 12:05:48
Did anybody have success with making one? I got the code from here and compiled it with make and avr-gcc. As I don't have a special avr programmer, I loaded Arduino ISP on a Arduino Micro and connected it to the Attiny. Using avrdude -v -P /dev/cu.usbmodem1101 -p attiny85 -c avrisp -b 19200 -U flash:w:/somepath/MacPlusRTC.axf I was able to successfully flash it to the Attiny. However, it doesn't appear to work now as I cannot measure the 1Hz pulse and I can also flash it again which shouldn't be the the case if the reset pin was successfully disabled. |
Posted by: robin-fo on 2022-04-12 14:00:03
Update: I was able to get a 1Hz clock using another Attiny and by appending -U lfuse:w:0xE2:m -U hfuse:w:0x5F:m -U efuse:w:0xFF:m to the avrdude command. However, my SE/30 still refuses to boot with this RTC chip. The curious thing is that it boots fine using a RTC chip from a Macintosh Classic... |
Posted by: pgreenland on 2022-11-07 02:47:24
@robin-fo Did you get this working on your SE/30 in the end? I've got a few battery bombed ones which I'd like to swap out the RTC on. |
Posted by: robin-fo on 2022-11-07 03:15:19
Nope.. I think it the RTC in the SE/30 is clocked faster than in the SE. I had to order a NOS part. |
Posted by: pgreenland on 2022-11-07 03:21:12
Ahh that would make sense.....I've been trying to build my own based on the few examples I found online.
One of them mentioned a max serial clock of 20Khz...I'm seeing closer to 250Khz. Thanks for backing up my suspicion that the clock rate was increased.
I failed to do the basic maths or how long have I got between clock edges....about 24 instructions at 8Mhz. I may need to write some assembly 😱. |
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