vectorboard core - for dout only

MIDIbox HUIs
1

i need to control only one dout module..

i connected only the pins

1,11,12,

13,14(crystal)

31,32

pin 19,21,22 to the dout

and midi in at pin 26

my pic works on a common pcb, but not on my vectorboard!!!

all the connections to the pic and to the optocoupler are right, the power level is ok… what am i missing?

2

What are you missing? Some parts maybe?

The pins you list are correct and should be sufficient, but it’s really hard for us to guess what the problem is without further info.

Do you get an upload request? Did you do the MIDI troubleshooting? Do you have pics?

3

ok, i added this connections

6 to 1kohm to 5v

18 to 10k to 5v

20 to 10k to 5v

and it works…

4

i wonder what is the very minimum configuration for the core, when a dout nly has to be controlled…

5

That’s interesting - I build a proto one without the additional pullups and it worked…

That _is_ the minimum config. You could get rid off the pullups if you by modding MIOS or just go with a way smaller chip (PIC16F88 comes to mind). Smaller chip would mean more programming though as MIOS won’t run on it.

6

I have seen that kind of failure when RB5/PGM/Pin 38 is allowed to float during programming, but here it is supposed to go to the LCD, which some people leave disconnected anyway.

The CMOS inputs will _usually_ float high all by themselves, but it not reliable. RB5 low can make the chip enter “Low Voltage Programming Mode” during initial programming.

If I were adding pullup resistors, that would be the first one, ESPECIALLY on a programmer board.. those few moments between erasing a chip and re-flashing it with the “LVP Disabled” option are the trickiest.