18F2580 with strange behaviour when using Hserin and RX interrupt

[PaulMaker]

Hi Richard,

thanks for the help.

According to the information on the display (when set to show the 4 incoming characters), 2 initial characters are being sent as carriage return (10 and 13) from the terminal.
That is why it's capturing 4 but i only use the last 2.

[HenrikOlsson]

Random ramblings and guesses here, take for what it is:

I'm trying to run a code that when an incoming 2 characters is received, it triggers the interrupt and reads the message.

That's not how it works. The ISR triggers when there's a byte is received. You can't configure it to fire after n character (short of setting up DMA and using that perhaps).

Typically, you'd write the interrupt to receive one byte at a time, putting them into a buffer (array) while looking for some sort of qualifier for "end of message" (number of characters, time-out, certain byte sequence, whatever). Once that qualifer is met you set a flag signaling the main rotuine that data is available. LCD updates etc is handled outside of the ISR.

You say that whatever sends the data sends 10,13 first, then two bytes of interest but you're not looking for the 10,13 sequence in order to "sync" and since you have a lot of slow code in the ISR it might get out of sync and therefor get stuck in the ISR since, once the interrupt fires your code expects 4 bytes.

If it gets 3 it'll sit there waiting for the 4th. Then a new burst of 4 bytes comes a long, where the first one counts as the 4th. Then the code moves on to to update the display while remaining three incoming bytes overflows the UART buffer because you're updating the display and/or executing a massive PAUSE in the ISR.

/Henrik.

[richard]

another issue

OSCCON =% 01110010 '8MHz INTOSC OSCTUNE=% 01000000 '




DEFINE OSC 8

will enable the PLL making OSC 32MHz

making the eusart defines incorrect

and

the oled display should only be initialised once
and you dont need to clear the entire screen for every write , just clear the area that needs to be updated
eg GLCD_CLR 0,1,127,8 ; clear a full width text line

[PaulMaker]

Greetings HenrikOlsson and Richard,

thank you so much for your help.

I will make a few changes and run some tests to see if I get it running correctly.

@Richard, regarding the osc settings, yes, you are correct,however, if I change to Define Osc 32 the code will run slower (tested before with pause 1000 and led blink). Weird things happen with this 18F2580 MCU

[richard]

if I change to Define Osc 32 the code will run slower (tested before with pause 1000 and led blink). Weird things happen with this 18F2580 MCU

pll only works with primary clock sources , if you set the int-osc as primary clock then it works as expected

DEFINE OSC 32


    OSCCON =% 01110000 '8MHz INTOSC 
    OSCTUNE=% 01000000 '

[PaulMaker]

Hi Richard,

you are correct (as always)!
I thought we had to choose internal insteal of primary since it's set to an internal osc.