"New" SD interface

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Re: "New" SD interface

Postby jdavis6809 » Mon Dec 02, 2019 11:46 am


going into production ?



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Re: "New" SD interface

Postby Dave » Mon Dec 02, 2019 6:16 pm

Another lovely card by Tetroid. :D

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Re: "New" SD interface

Postby Silvester » Mon Dec 09, 2019 12:39 pm

I notice that you didn't use a trimmer capacitor with the PCF8583 crystal ?

I built a Minerva Mk2 last year from discrete 74xx logic. Without a trimmer capacitor my PCF8583 clock ran very fast. With QL powered up it was 3 minutes fast per hour!, but only reducing to 20 seconds fast per hour when on battery.

I solved the 3min/hour problem by putting 220pF capacitor across PCF8583 pins 4 & 8 (noisy QL hardware). With a 30pF trimmer between pins 1 & 8 I was able reduce RTC error to less than 1 second a day :-)

I notice from a photo of real Minerva MK2 that they also used a trimmer.

BTW I thought I had a faulty NETwork until I realised if you initialise all RTC ram locations to 0, the NET number gets set to 0 upon each reset (should default to 1). This stops the TK2 network fileserver from working (SuperBASIC NET command disallows setting NET 0, but Minerva MK2 does, oops).

I'm not plugged into the Matrix so my responses may be delayed.

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