i2c LCD...

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cactusface

Senior Member
Hi All,
I just got one of these from China, it a i2c backpack that fits on to an LCD (the usual HD477*** type), Great I now only need to pins and not 7 or 8, but How would you program it?? The only other i2c I have used it the DS1307RTC? It says the address is 0x27 would I still use the same codes for DATA or COMMANDS...

Any help welcome.

Regards

Mel.LCDbp-1.jpg
 
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cactusface

Senior Member
eclectic said:
Any sort of datasheet?

e
Click to expand...
Hi Eclectic,
No! I don't think the chinese do data sheets, well not these, it cost me about £1 with free postage. I see rev-ed do an i2c version of their RTC module. Perhaps I can find some code for that?

@nick12ab Thanks I'll take a look this afternoon, I now have to go out and it's just started to rain!!!

Regards

Mel.
 
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nick12ab

Senior Member
cactusface said:
I see rev-ed do an i2c version of their RTC module. Perhaps I can find some code for that?
Click to expand...
Rev-Ed's i2c offering works completely differently. Rev-Ed's has been designed so that it is easy to use with the PICAXE system whereas the Chinese one has been designed for cheapness and the complexity of using it can be hidden behind a library when using the Arduino system.
 
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Puuhaaja

Senior Member
Rev-Ed's i2c offering works completely differently.
Click to expand...
When I bought my own I2c lcd board I thought it would work similar way as rev ed's but I was totally wrong. I found some testing codes here but They weren't easy to use.
 
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Paix

Senior Member
It seems that the price is not necessarily the same as the cost.

Whilst the price from China is around £1, the cost has to be paid elsewhere and perhaps by others before the eventual cost gets nearer to the price paid directly. Time is money and all that. A big salute to all those forum stalwarts and the Rev Ed team who make life easier for the majority of us.
 
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Rick100

Senior Member
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cactusface

Senior Member
Hi Paix,
Sorry I don't do politics or football!

Hi Rick100,
Yes and I mostly use Arduino now! but I have a friend who is still strong on the Picaxe, but not too good with the basic, so I wondered how picaxe would deal with the problem. On the Arduino forum as you may have read, some one has written code to guess the connections between the i2c expander and the LCD, and it solved my problem, perhaps Hippy's code is similar, must go and have a look. Here's a picture of my LCD which now shows the pin mapping the code found..

Again thanks for your help and advice, and yes a big thank you to people like Hippy and many others who have helped me in the past.

Regards

Mel.
LCDmapping.JPG
 
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westaust55

Moderator
There are at least two variants of circuit using an i2c expander chip to interface an LCD based on past threads I have helped with.
You need to ascertain the i2c chip being used, then the slave address, and finally the chip to LCD signal allocation before you will have any success in getting characters on the screen.
 
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Rick100

Senior Member
If you try this display on the picaxe , you need to multiply your address by 2 . This will shift it left 1 bit to allow for the read/write bit . In the picture of your display it says the address , found by the lcdguesser program is $27 , so it will be $4E on the picaxe .
 
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