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 Re: progamming PCF8574 Kategorie: Programmierung Basic (von rien an harmelen - 23.11.2004 9:52)
 Als Antwort auf Re: progamming PCF8574 von Carsten - 22.11.2004 15:18

> Hello,
>
> hard to say what's wrong with THIS program, (I do not have the book [1]), but you can get addittional help and tips, when you check the documentation of M-Unit 2.0, even if you don't have it. It provides a port module (Conrad# 198848) where you can see in the documentation if you use the 8574 properly (pins etc.)
>
> Also there are demo programs available for the use of this module, so you could use this demos and replace the print# / i2c start / i2c stop - statements inside by subroutines (gosub) that do the same. So you see if your 8574 Hardware is responding properly.
>
> Carsten
>
> > Please, who can help me to program a  PCF8574. What is wrong in the program given below. I like to turn a stepper connnected to P4-P7 (of the PCF8574) when a switch) connected to P3 is depressed. P0/P3 are connected with a pull-up to 5V . By pressing the switch P3 will be connected with a pull-up to 5 V
> >
> > define .......etc
> >
> > SDA=on
> > SCL=on
> > zaehler=&B00001000
> >
> > #loop
> > 'reading ON/OFF of P3
> > gosub start
> > datenW=65
> > gosub I2C_write
> > gosub I2C_read
> > gosub Noack
> > gosub Stop
> > if datenR=&B00001111 then gosub motor else goto loop
> > goto loop
> >
> > #motor
> > zaehler =zaehler shl 1
> > gosub start
> > datenW=64
> > gosub I2C_write
> > datenW=Zaehler
> > gosub I2C_write
> > gosub stop
> > if zaehler=&B10000000 then zaehler=&B00001000
> > return
> >
> > #start
> > please refer to [1]
> >
> > #stop
> > please refer to [1]
> >
> > #I2C_write
> > please refer to [1]
> > read instead of daten : datenW
> >
> > #I2C_read
> > please refer to [1]
> > read instead of daten: datenR  
> >
> > #Ack
> > please refer to [1]
> >
> > #Noack
> > please refer to [1]
> >
> > [1] Messen, Steueren, Regeln mit dem C-Control/BASIC System von Kainka (page 163 u.w.)
> >
> > thank you very much
>

Hallo Carsten,,

Thank you for your answer

Question1
Regarding  [1] : please refer to the answer I have given to Achim

Questikn2
Next to other documentation I have also " studied " the documentation of the M -unit-2, but without any result

Question3
It is not a hardware problem, as there is nothing wrong with the I2C-bus PCF8574. The problem is the software. If you replace the #loop by:

#loop
goto motor
return

then the stepper runs merrily.

The problem in #loop is  reading the position of the switch (ON or OFF)  connected  (in this case) to P3 of the PCF8574
 
I hope you can help me

kind regards rien van harmelen

Kind regards  




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Re: progamming PCF8574 (von Carsten - 23.11.2004 13:07)