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My first foray into I2C on the F452 is turning into something of
a test of patience. Bit-banging on older PICs worked out OK.
I've not used its MMSP before, but I thought I'd done enough
reading beforehand to get it going. Set up code shown below.

I just can't get a low ACK from the slave on the 9th clock and
the whole thing stalls

What piece of the jigsaw am I missing ? I've tried a heap of
arrangements but the analyser grab always looks depressingly
the same ;-(((

PCB traces are ~ 50mm (SDA signal on pin 5, SCL pin 6), 5V,
2k2 pullups on each, 0.1uF ceramic across 5V/0V pins, no noise
detected on Vcc

TIA

         mov     b'11011000',trisc  ;SDA, SCL as i/p

;        Read address A3
;        Write address A2

         mov     b'00101000',sspcon1
;                    1               SSPEN
;                      1000          master

         mov     b'10000000',sspstat
;                  1                 slew rate off

         mov     0x61,sspadd        ;I2C baud rate, 100kHz

         bsf     portb,3      ;analyser trigger
         nop
         bcf     portb,3

         bsf     startb       ;send start bit
         btfsc   sspcon2,sen
         bra     $-2

         mov     0xa2,sspbuf  ;slave address
         btfsc   sspstat,r_w
         bra     $-2

         bsf     portb,3

         btfsc   sspcon2,ackstat   ;wait for ACK
         bra     $-2

         bcf     portb,3        ;never happens

==============================================
Research is what I'm doing when I don't know what I'm doing
- Wernher von Braun

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