Framing error if I disable transmitter after shift register is empty?

[Demon]

IT'S THE DARN PIC !

I swapped the coding between the 2 PICs, and PIC #1 now has a framing error every time it tries to disable the transmitter.




I'm going to swap it for another unit and see if that changes things.

[richard]

when you disable the transmitter how are you setting the tx pin
code ?

[Demon]

when you disable the transmitter how are you setting the tx pin
code ?

I'm not doing anything to it. Should I?

[richard]

explain how disabling tx-module sets the pin to "tristate"

[Demon]

I'm not using tri-state yet, cause for now I have only two PICs talking, and they're not sharing any lines (but I will be the future, hence why I'd like to master enable/disable of transmitter).

It's direct TX-to-RX and RX-to-TX with 1 set of 4K7 pull-ups.

Right now it's only an exercise.

[richard]

It's direct TX-to-RX and RX-to-TX with 1 set of 4K7 pull-ups.

yet when tx is disabled the pin is hard driven to logic 0 , explain how disabling tx-module sets the pin to "tristate"

[Demon]

I'm not setting anything to tri-state, yet. Using TXSTA.5 = 1 / TXSTA.5 = 0 is just preparing myself for when I will use Usart pins in tri-state.

I thought I could just turn Usart TX and RX on/off whenever I wanted (when nothing was in the buffer).

Or was that a wrong assumption?

[Demon]

Hmmm, I moved PIC #2 up in PIC #1 spot, and put in a new unit in PIC #2 spot.

PIC#1 can now disable transmitter at will, YAY! So that confirms that there's nothing on the breadboard interfering with that PIC.

New PIC #2 gets a framing error, but neither of the PICs freeze now (I put the blinky channel right under each PIC).




PIC#1:

Start:
    TXSTA.5 = 1                     ' TXEN: Transmit Enable bit
    hserout [   "[1]"    ]                             
    while TXSTA.1 = 0               ' Check TRMT: Transmit Shift Register Status bit
    wend
    TXSTA.5 = 0                     ' <----- Causes Framing error after last byte !

    hserin [ wait("["), STR RecvData\11\"]" ]

    TXSTA.5 = 1                     ' TXEN: Transmit Enable bit
    hserout [   "[2]"    ]                             
    while TXSTA.1 = 0               ' Check TRMT: Transmit Shift Register Status bit
    wend
    TXSTA.5 = 0                     ' <----- Causes Framing error after last byte !

Mainloop:
    BlinkLED = 1
    BlinkLED = 0
    GOTO Mainloop
end

PIC #2:

@   INT_ENABLE   RX_INT
    goto Start

ReceiveInterrupt:
    hserin [ wait("["), STR RecvData\11\"]" ]
    UsartFlag = 1
@ INT_RETURN

Start:

Mainloop:
    LEDblink = 1
    if UsartFlag = 1 then
        TXSTA.5 = 1
        hserout [   "[0]"  ]                            
        while TXSTA.1 = 0              ' Check TRMT bit
        wend
        UsartFlag = 0
        TXSTA.5 = 0
    endif
    LEDblink = 0
    GOTO Mainloop
end

Might have a few ideas more ideas to try out...