Problems when changing from O/P to I/P

[Graham Bremner]

Hello,

I am trying to link a pic16F877 to a sensirion SHT11 humidity sensor. I am basing my code on the sample code for an 80c51 processor.
It is a 1 wire interface, used for both reading and writing.
Initially I set it up using.

set_tris_b(0x01);
#USE FAST_IO(B)

next I send a data sequence to the device on RB2, then

set_tris_b(0x05); //RB2 as I/P, already given the name data
#USE FAST_IO(B)

while (DATA==1) {
delay_ms(1); }

This should loop until data has gone low but it exists this
loop straight away, when data is still high.
I dont think it is a timing problem as data is high for 5ms before the loop is called.

Any ideas??

Thanks
G Bremner
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This message was ported from CCS's old forum
Original Post ID: 12369

[Hans Wedemeyer]

:=while (DATA==1) {

What code are you using for DATA ?

Is it a #define or what ?
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This message was ported from CCS's old forum
Original Post ID: 12381

[Graham Bremner]

Hi,

Yes, I am just using #define.

I have got round the problem by using 2 pins. One for o/p and 1 for I/P. This now gives me a 2 wire connection to the pic and its works fine. Using an extra line but I had 2 spare anyway.

Thanks for your intrest

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This message was ported from CCS's old forum
Original Post ID: 12419

[PCM programmer]

:=Hi,
:=
:=Yes, I am just using #define.
:=
:=I have got round the problem by using 2 pins. One for o/p and 1 for I/P. This now gives me a 2 wire connection to the pic and its works fine. Using an extra line but I had 2 spare anyway.
:=
--------------------------------------------
I once posted some notes on how to convert their sample driver
for the SHT11 (written for the Keil compiler) to CCS.
<a href="http://www.pic-c.com/forum/general/posts/3989.html" TARGET="_blank">http://www.pic-c.com/forum/general/posts/3989.html</a>

Here's their sample driver:
<a href="http://www.sensirion.com/en/pdf/ApplNote_SHTxx_c1.pdf" TARGET="_blank">http://www.sensirion.com/en/pdf/ApplNote_SHTxx_c1.pdf</a>
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This message was ported from CCS's old forum
Original Post ID: 12442