Read Modify Write problem?

[Darrel Taylor]

Hi Mark,

Instead of trying to set the PORT's either high or low, set the PORT to the active ON state, then set the TRIS bit to INPUT(1) or OUTPUT(0) to control the LED's. No R-M-W that way.
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[markedwards]

Thanks Darrel,

Is this what you meant?
Variable X0 is the segment pattern and is sent to the output ports.
TRISB. I use OR to maintain portB.1 as input
TRISA. I use OR to maintain PortA.2 and PortA.3 as inputs
Is there an better approach?



'initialize ports
TRISA = %00001100 'configure port A outputs = 0
TRISB = %00000010 'configure port B outputs = 0

Thanks,

Mark

'write segments to ports A and B
PORTB.0 = X0.0 ' Send segments to LED 0 = ON
PORTA.4 = X0.1
PORTA.6 = X0.2
PORTB.3 = X0.3
PORTB.4 = X0.4
PORTB.5 = X0.5
PORTB.6 = X0.6
PORTB.7 = X0.7

TRISB = X0 OR %00000010 ' OFF segments = 1 (set to inputs)
X1=X0 AND %01010000 ' isolate X1= PortA.4 and PortA.6 bits
TRISA = X1 OR %00001100 'maintain PortA.2 and PortA.3 inputs

[Darrel Taylor]

uh, nope.

I was thinking something more like this.

PORTA = 0
PORTB = 0

'write segments to ports A and B
TRISB.0 = X0.0 ' Send segments to LED 0 = ON
TRISA.4 = X0.1
TRISA.6 = X0.2
TRISB.3 = X0.3
TRISB.4 = X0.4
TRISB.5 = X0.5
TRISB.6 = X0.6
TRISB.7 = X0.7
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[markedwards]

Thanks Darrel,

That is much cleaner! I will give it a try.

Mark