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When you get all 0's, it usually means one of two things.
1) The SDA,SCL pins still have the analog mode enabled.
2) There aren't any pull-ups, or they pull-down.
If you have a voltmeter, check the voltage on the SDA,SCL pins.
They should be above 4V when no data is being transfered.
But I'm betting on analog mode.
<br>
DT
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As said in post 1#, both (SCL and SDA) are pulled up with 2 2k2 resistors, one for each. So when the lines are inactive you can measure 4,98V there, so that suggest also that the problem has to be somewhere else. I have also looked with an oscilloscope on the active signals, but being not so familiar with the inner live of the I2C protocol, can't tell if there would be something wrong, to me they look "normal". From the clock line I could calculate a clock frequency of something around 65kHz +/-20%. Is that OK?Originally Posted by Darrel Taylor
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Then it must be 1).
Put this line at the top of your program.
ADCON1 = $F ; set all pins to digital
<br>
DT
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Copy-Pasted that ADCON1... and that could have helped but unfortunately it did not help, nothing changed
The problem is somewhere else, but where?
Does that 65KHz sound correct? On what frequency should the clock run under those two I2C routines (I2CREAD I2CWRITE), where could one find any info on that. Tried also DEFINE I2C_SLOW, but again without success... What can I do? The expander is kind of alive because it does not throw you to the error label....
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No 65khz does not sound right, and ...
It doesn't throw you to the error label because it always reads 0's on the pin.
An ack from the device is a low pulse. As long as it sees a low when it expects an ack, it will never jump to the label.
OK, it's time for you to pony up some of the info you've been leaving out.
What are your CONFIGs?
What cyrstal are you using?
What DEFINE OSC are you using?
What pins are the SCL and SDA on?
And the rest of the code.
<br>
DT
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So, back to the basics.
If not 65kHz is correct, then what should it be?
If I change the device address from $40 to something else for ex. $45 it will throw the program to the error label. That behavior sounds "healthy", doesn't it?
By CONFIGs you mean? See post #1
The crystal is 12MHz
DEFINE OSC 48
The SDA,SCL pins are connected correctly to pins 33,34 + 2x 2k2 pull-ups
Using also Microchip USB HID bootloader v2.2
I2Creg = OLAT1 : I2Cbyte = $ff : gosub writeioextender: pause 20
I2Creg = IODIR1 : I2Cbyte = $ff : gosub writeioextender: pause 20
The current test loop is here:
Loop:
gosub getbattery
if onoffpressed = 1 then powerout = 0
I2Creg = GP1 : gosub readioextender' to IOEbyte
pause 20
lcdout cmd,home3, dec battery/10, ".",dec battery//10,"V ", dec w/100," ", _
dec onoffpressed,cmd,home4, hex2 IOEbyte," "
goto Loop
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No look at this thread.
http://www.picbasic.co.uk/forum/showthread.php?t=543
If you do not believe in MAGIC, Consider how currency has value simply by printing it, and is then traded for real assets.
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Gold is the money of kings, silver is the money of gentlemen, barter is the money of peasants - but debt is the money of slaves
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There simply is no "Happy Spam" If you do it you will disappear from this forum.
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A quick test here on a 4550 at 48mhz, shows ~250khz clk.
For the configs, I didn't know you were using the USB bootloader. The configs will be whatever the bootloader was programmed with. You'd probably need to read back the chip to find out what configs are set.
I was hoping for more of the program, there's a lot of stuff missing, and you never know, 1 statement could change everything.
Since you are getting all 0's. Maybe you should just try to read the RB0 pin without I2C, as a test. There's a pull-up on it, if you only read a 0, then something's still not right.
<br>
DT
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