Losing data when extracting bytes from words - 16F18855

[Demon]

more robust demand/response handshaking...

Once I TX data, I waited till TX complete:

The TXIF flag does not indicate transmit completion (use TRMT for this purpose instead).

(16F18855 p.146)


Then I sit in a loop waiting for RX interrupt:

To ensure that no actual data is lost, check the RCIDL bit to verify that a receive operation is not in process...

(16F18855 p.553)

;--- Interrupts ----------------------------------------------------------------

RXInterrupt:
    hserin [ STR MsgData\3  ]

    while BAUDCON1.6 = 0                        ' Check RCIDL bit
    wend

    RXoccurred = 1                              ' Set flag
@ INT_RETURN
    
;--- Subroutines ---------------------------------------------------------------

SendData:

    hserout [   MsgData[0], MsgData[1], MsgData[2]   ]                             

    while TX1STA.1 = 0                           ' Check TRMT bit
    wend

    while RXoccurred = 0                       ' Check for interrupt
    wend

    RXoccurred = 0                              ' Set flag
    ADCchange = 1
RETURN

I turned the pot pretty fast and this is the fastest interval I got from start of 1st TX to start of 2nd TX:




I'm still studying your TX/RX module. At least now I have a control that I can compare with.

[Demon]

To make sure I wasn't losing data, I returned the data I received. I also used the 45mm slide pot for another speed test; zipping that sucker as fast as I could: 1.234 mSec from start to start of TX.

These are the signals, in case the text from Saleae probe is not clear enough (they get a little fudgy or some reason):

Primary PIC:
- TX

Secondary PIC:
- RX-INT
- LCDout ADC values
- TX confirmation
- LCDout "X" indicator (this is for testing only, to see if other pots "jitter")

Note that data is not lost even if bottom LCDout overlaps into next message.

[Demon]

I figure I'd push the envelope a bit faster with that 45mm slide pot; 1.228 mSec from start to start of TX.

I also took out that 2nd LCDout with the "x" indicator, it was just for testing anyways.

This time I went faster than the previous ADC increment changes of 3, I managed to go to 7 and still no data lost: