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February 6, 2012
about 4 years ago
I managed to set it so i2cfast but slow also worked.
Software look alright…
- did you perhaps reprogram the i2c address?
- did you power the display board? ;-)
- I managed to get some 0000 displayed when touching the serial Rx pad, waking up the display and showing that it’s ok
- double/triple check the connections :-) Crossed SCL/SDA?
[SOLVED] Quick eureka. Although I don’t really understand it. When removing the address (0) from the hi2cout command, it seems to work. As if it’s interpreted as a data byte (?).
hi2cout (“x”, “0”, “x”, “8”) ; this now works
Hope this will help other PICAXE/i2c/7-segement users.
[SOLVED] I fell into the “i2c addressing” trap… D'oh!
The Sparkfun datasheet mentions 0x71 as the slave address, but this is a 7-bit address.
The PICAXE command requires an 8-bit number so you have to shift the address left 1 bit.
That solved it. So the 0x71 becomes 0xE2 (confusing in my opinion). And yeah…it’s in the command info…which is clear…when you understand the problem… :-)
The PICAXE BASIC command should have used the i2c addresses directly, in my opinion, like the Arduino Wire library. Why the need to bother the high-level BASIC command with low-level i2c protocol r/w bits.
I did notice that I now have to use a 0x76 reset command when setting the 4 digits in a while-loop:
hi2cout 0, (0x76, “x”, “0”, “x”, “8”)
hi2cout 0, (0x76, “x”, “0”, “x”, “0”)
Without the 0x76 the display doesn’t seem to use the correct cursor position and the numbers started to shift. Not sure why that is but I’ll probably get that eureka next week :-)
Is there anything special about the new version of these displays? I’m having trouble getting it to work with i2c which I need. I’m using a Picaxe micro. I only need +, -, SCL and SDA right?
In Picaxe BASIC I use something like:
hi2csetup i2cmaster, DISPLAY_I2C_SLAVE_ADDRESS, i2cslow, i2cbyte ; address is 0x71
hi2cout 0, (0x76) ; reset display
hi2cout 0, (“x”, 0, “x”, 0) ; initial value
but for some reason this isn’t working. Anybody else using this device in combi with a Picaxe and i2c?
What about the slow/fast and byte/word i2c protocol settings for this device?
The Picaxe itself is working fine, happily blinking a LED on a different port. The code for changing the display has no effect though.
I’m using a 4.8 V wall adapter. That shouldn’t be a problem right? The online example however mentions:
“Also make sure to power the display at 5V!”
Wires are: SDA to SDA, SCL to SCL and two 4k7 resistors as described in Picaxe manual.
I’ve bought two displays and both of them aren’t working (all LEDs stay off) so it would be strange if both i2c headers are soldered incorrectly. Power is also ok, so those headers are soldered ok; when I touch the serial Rx pad with my finger the display turns to all zeros just fine.
What am I missing?
about 4 years ago
It would be nice to see a 30 AWG set as well; I’ve bought this pesky SMD component…
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