SPI instead of SHIFTOUT - MAX7219

[Darrel Taylor]

What I did in my code is:

INTCON = %11000000       ' Set the interrupts, i.e. enable GIE and PEIE
SSPIE = 1                       ' Enable SSPIE interrupt

Is there any mistake I have overlooked in my interrupts setting?

NO! You don't want to do that.

You just use the flag to tell when the SSP is finished.
If you enable interrupts without any interrupt Handlers, it goes off into never never land, overflows Stacks and generally just doesn't work.
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[Momboz]

NO! You don't want to do that.

You just use the flag to tell when the SSP is finished.
If you enable interrupts without any interrupt Handlers, it goes off into never never land, overflows Stacks and generally just doesn't work.
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Sorry DT

I wasn't complete in my previous answer.

The first thing I did was to test with the addition of the while loop as you proposed and it wasn't successful, i.e. No toggle on PORTB.0 signal. It looks like the While loop is blocking the process (or like SSPIF is never set). if I suppress the while loop the PORTB.0 will toggle again.

That's the reason why I thought about setting the interrupts.

[falingtrea]

Here is some sample code from meLabs. Maybe that would be of help to you.

http://www.melabs.com/resources/samples/pbp/spimast.bas
http://www.melabs.com/resources/samp...p/spislave.bas

[Momboz]

Here is some sample code from meLabs. Maybe that would be of help to you.

http://www.melabs.com/resources/samples/pbp/spimast.bas
http://www.melabs.com/resources/samp...p/spislave.bas

@falingtrea

Many thanks for the advice. I have seen these examples and I couldn't succeed since I need a peer to talk to via the SPI. I am intending just to drive a MAX7219.

Vielen Dank nochmals.

[Darrel Taylor]

It looks like the While loop is blocking the process (or like SSPIF is never set). if I suppress the while loop the PORTB.0 will toggle again.

That's the reason why I thought about setting the interrupts.

Works fine here.
Ran your program (with the suggested changes) on an 877, and It sends data from the SSP and blinks the LED.

It's A VERY FAST blink. Not visible to the naked eye (or clothed ones).

Try putting a PAUSE 200 in the Main Loop.
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[Momboz]

Works fine here.
Ran your program (with the suggested changes) on an 877, and It sends data from the SSP and blinks the LED.

It's A VERY FAST blink. Not visible to the naked eye (or clothed ones).

Try putting a PAUSE 200 in the Main Loop.
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Dear DT

I would like, first, to thank you very very much for your support and then I wish to give you a feedback on how far I went with my SPI interface.

After some investigation I could find the reason of the problem I have making SPI running on my board. It is a hardware issue. It's the way I am using the Melabs PICPROTO-USB board. That doesn't mean that Melabs PICPROTO-USB board is faulty.

On that board you have the possibility to use the USB board in high speed. Therefore you need a capacitor C7 (0.470 µF) as shown in the documentation of that Melabs board (http://www.melabs.com/downloads/ppusbsch_06.pdf). This seems to prevent the SPI interface for running properly. I have taken the C7 away and everything went fine with SPI interface.

Maybe we will have a new Melabs board with a jumper that could leave this capacitor out when using the SPI interface

For the time being I have to make a choice for by Melabs board usage: either using USB high speed (and put the C7 capacitor) or using SPI (and take away the capacitor).

Once again many thanks for your help.

Best wishes / Momboz

[Darrel Taylor]

Good find Momboz!

I see you mentioned the PICPROTO-USB up in post #3.
But I never even looked at the schematic.

For the time being I have to make a choice for by Melabs board usage: either using USB high speed (and put the C7 capacitor) or using SPI (and take away the capacitor).

If you're using a PIC with USB, the SPI interface will be on different pins, so it shouldn't be a problem.
But you're right. meLabs should have put a jumper in there for the capacitor.

Cheers!