read temperature

[mister_e]

mmm, the only lasts things that sping to mind is ...

1. is your supply line is neat and clean ?
2. what about if you place 0.1 uF + 10 uF(close to PIC and close to sensor)
3. are you sure of your Sensor pins... can it be reverted

[breeno]

after days of tests.... nothing...
i don't know why with the noread label i have "no connection" while without noread label i have always "2" on LCD.
i have reverted all pins, filtered supply line and sensor supply, i have tried every configuration option, i have inserted pauses betwen every instruction, i have changed resistor to 4k7..... always the same thing.....
any idea?

[Segeer]

Hi!

You're using device adress $9A thats mean label on your sensor is TC74A5 if not, you have found out your problem. Anyway you're using same adress-command for reading as for writing that's error too.

For TC74A0 is adress 1001000* (thats mean $90 for writing $91 for read from device)

For TC74A1 is adress 1001001*
For TC74A2 is adress 1001010*
For TC74A3 is adress 1001011*
For TC74A4 is adress 1001100*
For TC74A5 is adress 1001101*
For TC74A6 is adress 1001110*
For TC74A7 is adress 1001111*

* is R/W, place 1 for reading from TC74, 0 for writing.

Anyway i'am using 4,7k pullup on both of pins.

This code is working for me (replace device adress if you've another):

BStart ; initiate i2c start
i2cwrite sda,scl,$90,$1,[$00] ' Place in normal operating mode
BStop ; stop i2c
Pause 10
BStart ; initiate i2c start
i2cread sda,scl,$91,$0,[temp] ' Read temperature
BStop ; stop i2c


Hope that will help you...
(and sorry for my english)

Milos

[Acetronics2]

Hi, Milos

Many Thanks for that useful tip.

BUT did you notice the last post was dated ... - 23rd February 2005, 12:51 ???

Alain

[Segeer]

Hi, yes i know, but i was searching by google for "TC74 picbasic" today and this topic is still one of firsts results.

Problem has not been still solved (for 5 years). It's doesn't matter how old is it -it still can be googled, so it will be helpful for someone maybe (in next 5yr) No?

Anyway i had to wrote answer -for peaceful sleeping ))

[Solomon]

Hi Segeer, I like your attitude. It is the right one, man. I am trying to implement the tc74 and because you posted the answer, helps me alot. Great stuff. One can just identify a true engineer in his attitude.

I am using PICBasic Pro and will try your code today.

Thank you again. I will post my PICBasic Pro Code for someone else in the future as well.

[fratello]

I will post my PICBasic Pro Code for someone else in the future as well.

I like this attitude too; I wait for complete code, as good example for further projects !