I2C Slave with a PIC

[Kamikaze47]

Thanks for looking DT. I'm currently running the above code "as is" on 2 breadboards side by side.

Still losing a byte every time I do an i2cread.

I tried reading one byte at a time instead of six, and I get: 1, 3, 5, 1, 3, 5. So no matter how many bytes I receive at once, it always skips the byte immediately proceeding those bytes.

*edit* My circuit is identical to yours there DT except for 10mhz crystals + caps, and I only have an LCD on the master PIC.

In case its relevant, these are my configs:

        __CONFIG    _CONFIG1H, _OSC_HSPLL_1H & _FCMEN_OFF_1H & _IESO_OFF_1H
        __CONFIG    _CONFIG2H, _WDT_ON_2H & _WDTPS_512_2H
        __CONFIG    _CONFIG3H, _CCP2MX_PORTC_3H & _PBADEN_OFF_3H & _LPT1OSC_OFF_3H & _MCLRE_ON_3H
        __CONFIG    _CONFIG4L, _STVREN_ON_4L & _LVP_OFF_4L & _XINST_OFF_4L

Hey Kamikaze,

I didn't see a problem from just looking at the code, so I ran it in the simulator.
And I don't see a problem there either.

On the master I get " 1 2 3 4 5 6".
It does not change.

I only added a toggle in the Master's main loop to verify it was looping.
And a toggle in the Slave's handler, to verify the transfers.

Is there something you stripped out before posting that could have caused it?

Attachment 4704

[Bruce]

Have you looked at the errata sheet for the silicon rev you have? This series has a lot of issues with the MSSP module & I2C.

[Kamikaze47]

I'll have a look at that errata sheet as you suggest.

Incidentally, DT: What program do you use for PIC simulation? It looks like a handy tool to have.

[Darrel Taylor]

Incidentally, DT: What program do you use for PIC simulation? It looks like a handy tool to have.

It's Proteus VSM, and it's extremely handy.

My breadboards are all covered in a layer of dust.
They don't get used much anymore.

[Kamikaze47]

It's Proteus VSM, and it's extremely handy.

My breadboards are all covered in a layer of dust.
They don't get used much anymore.

Unfortunately, as I feared, the price is pretty steep.

[Darrel Taylor]

That was my initial reaction too.
But I've since found that it is EXTREMELY inexpensive, if you consider the value vs. cost.

You can't even buy a decent Digital O-Scope for that much.
But Proteus gives you Multiple 4ch-DSO's, 32ch-logic analyzers, voltmeters, ammeters, virtual terminals, signal generators, pattern generators, power supplies, I2C debuggers, SPI debuggers, frequency counters ...

There's a whole boat load of PIC's to choose from, plus all the other chips and discrete parts.
You can simulate multiple PIC's in the same circuit simultaneously.

And with PBP 2.60a, it integrates right into the MPLAB IDE for step by step debugging.

$479 gives you all that and either the 16F's or 18F's.
Can't get much cheaper than that.

I should be getting a commission, I sound like a commercial.

P.S. You can download the Demo Version and run your PBP programs on the sample circuits. You just can't modify the circuit.
    Take a test drive.
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[aberco]

Would it be possible to easily change one of these example routines to use the MSSP module for I2C Master?

In my program I change the clock speed from 12MHz to 250kHz, and it takes about 50ms to execute an I2CWRITE command at the slower speed. I measured the I2C clock to be about 800µs which is 1,2kHz... that's not much. I'm guessing that the PBP command includes it's own set of hardcoded delay... I'd like to save power, and if running I2C at 100kHz, I could get the PIC back to sleep 100 time faster.

I'm understanding quite well changes to make in registers to configure the hardware part, but I must say that when it get to assembler I don't understand too much of it right now...