Hi,
can you make the generated assembly files / listings (or their contents)
for both the working and the failing case accessible somehow? I think one
cannot attach files here, but posting (or publishing via
drive/dropbox/pastebin/...) at least the assembled main function would help
to check for differences.
Best regards
Raphael
On Tue, Jan 21, 2020, 15:27 Richard Molton <li...@richardmolton.plus.com>
wrote:
> I'm new to both sdcc and I2C. Trying to write code to read data from 2
> I2c devices, master is pic16F887. Main part of code:
>
>
>
> void main (void)
> {
> uint8_t theta, dummy, bitdata, position;
>
> PORTB = 0;
>
> OSCCON = 0b01100001; // 0x7f Set CPU to 4MHz
>
> io_setup();
>
> I2C_Initialise(15) ;
>
>
> while(1) //repeat endlessly
> {
>
> while(PORTB & 1 ) // hold while switch on demo board not
> pressed
> {
> ;
> }
> PORTD = 80;
> while((PORTB & 1) == 0) //hold while switch is pressed
> {
> ;
> }
> //continue when button released
>
> I2C_Start() ;
> I2C_Write((0x71 << 1) | 1) ;//send device ID and'read'
> bit
> bitdata = I2C_Read(1) ; //read first byte
> position = I2C_Read(0) ; //read second byte
> I2C_Stop() ;
>
> I2C_Start() ;
> I2C_Write((0x4f << 1) | 1) ;//send device ID and'read'
> bit
> theta = I2C_Read(1) ; //read byte 1 / ack
> dummy = I2C_Read(0) ; //read byte 2 / nack
> I2C_Stop() ;
>
>
> //PORTA = 0;
> PORTD = bitdata ; //3c
> msleep(500);
> PORTD = position ; //7e
> msleep(500);
> PORTD = theta; //15 approx
> }
> }
>
> The device waits until a switch on B0 is pressed and released, then
> reads 2 bytes from one device at address 1110001, and 2 (1 plus a dummy)
> fron a LM75 temp sensor at 1001111.
>
> The last block of commands just uses PORT D to display the reads
> sequentially to see if it all works. Not bothering to display the second
> byte of the LM75.
>
> As listed above, it just displays the last reading and ignores the first
> two. If the PORTA=0 command is reinserted (it has no purpose in the
> prog) everything is displayed OK. Pressing the 'go' button repeats this
> result.
>
> With PORTA commented out (or left in) , it will happily display
> sequences 'bitrate bitrate theta' , 'position position theta', 'position
> bitrate theta' but it refuses with 'bitrate position theta'. Repeat
> pressing, repeat output.
>
> I can find no reason for this but am reluctant with my very limited
> experience to blame the compiler. . . but could this be the problem?
> sdcc is being used as downloaded with no fancy settings.
>
> Any suggestions appreciated. Well, almost . . .
>
>
>
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>
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