Vince Briel Replica 1 ten noise problem / use of lower case

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Vince Briel Replica 1 ten noise problem / use of lower case

I hope it will help someone...

 

I bought a replica 1 ten from Vince Briel but it never really worked :(

each time I had a hand near the board I had an apparent repeated reset

the machine displaying

\

\

.... 

indefinitely....

 

finally I discovered the source of the problem some noise received by the strobe pin  (pin 40 6821)

I solved it by adding a 10k resitor on the back of the board between PIN 1  (gnd) and pin 40 (CA1/strobe) of the 6821

now it is parfaitly stable...

 

the problem is more complex, in fact the propeller code is puting the direction port of the proppeller in output to send a character

to the PIA and then put it back in input mode

so we have CA1 in input mode and most of the time strobe on the propeller in input mode

in that case CA1 is receiving noise....  (the 10k resistor works)

it is possible to avoid adding a resistor by modifying the propeller code to let the direction port in output mode

but in that case it breaks the ascii keyboard port

 

I tried to removed the 10K resistor I added and flashed the propeller with last code from Reactive micro

modified to have the keyboard direction pin always on output... it works perfectly

the machine is rock stable but the ascii keyboard port is unusable

 

I try to find a better fix

 

by tweaking the propeller code I have been able to push it to 3Mhz and 57600 bauds

 

does anybody know if there is a way to automatically convert lowercase into uppercase in the propeller code ?

it's boring to use shift or caps lock all the time to type a program

(lower cases are simply ignored)

 

 

 

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Last seen: 1 month 1 week ago
Joined: Mar 20 2014 - 15:43
Posts: 75
replica 1 ten / plus fix

Finally to keep the same functionality

the best fix for the noise on strobe is the 10k resitor on the back of the PIA between pin 1 and 40

 

I have not found any way to modify the spin code without loosing the ascii keyboard

 

for the use of lower case in place of upper case I just added:

if   serdata > 96 and serdata < 123

     serdata -= 32

 

just before sending the data to the PIA

in file: replica 110REV03.spin

 

 

 

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Last seen: 1 month 1 week ago
Joined: Mar 20 2014 - 15:43
Posts: 75
noise problem from DA line

once the strobe problem was fixed I discovered that from time to time I had  a garbaged screen

this garbage appeared in conditions similar to the strobe noise

it is due to the DA line  going up and down

 

I solved this problem by adding a   10k between  DA line pin 17  PIA and GND pin 1 PIA

 

after having done this 2 modifications the machine is working fine and I've not seen any new sources of noise

 

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