Bug on I2C lCD

[ylanchec]

Hi,
I have open an existing working project from FC7 to FC8.
But now the I2C LCD does not works.
The LCD is a DFRobot (with PCF8574) and the card is a MEGA.

sch.png

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I have compare the i2c dialog on both cases :
Good (on FC7) :

good_i2c.png

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Bad (on FC8) :

bad_i2c.png

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As you cas see there is a value added each time.
Best regards
Yannick

[Jan Lichtenbelt]

Hi ylanchec

RW should always be at 0V (or GND). It is better to remove the conenction to P1 of the microchip.

Kind regards

Jan Lichtenbelt

[ylanchec]

Hi Jan,
Of course i can connect RW to GND in Proteus, but on the real card i can't modify this.
The bug seems to comes from the i2c dialog, there are too many bytes in the command. (the last byte)
Best regards
Yannick

[Jan Lichtenbelt]

Dear ylanchec

Show us the flowcode and perhaps someone can help you with the software

Kind regards

Jan

[ylanchec]

Hi Jan,
You will find here a zip file including :
- 1 simple fc7 writing "hello" on a LCD I2C --> HEX file
- the same file renamed and opened with fc8 --> HEX file
- proteus 8.8 file with Arduino mega linked to fc7 hex --> WORKING
- proteus 8.8 file with Arduino mega linked to fc8 hex --> NOT WORKING
The problem is the i2c dialog... not good on lcd on fc8 !

Test_LCD_I2C_FC7_FC8.zip

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Best Regards
Yannick

[ylanchec]

Software FC7 and FC8

logfc8.png

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logfc7.png

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[ylanchec]

On proteus 8.8

fc7.png

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fc8.png

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On FC8 there is too many bytes in a dialog !

[ylanchec]

Good :

fc72.png

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Bad : a 0x00 is immediatly sent after the good value !

fc82.png

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Best regards
Yannick

[Benj]

Hi Yannick,

I've posted a new version of the v8 component to the update system now. It contains a new property to decide if the backlight is controlled via the main display communication. When set to "No" this should be identical to the v7 component.

Let us know how you get on.

Hopefully the problem is with Proteus and the v8 component would have worked fine with actual hardware. Can you confirm if you have tried on hardware or not and how you got on.

[ylanchec]

Hi Benj,
Thank you for your quick response.
I have tested your new update and it's ok on proteus.
I'm going to test on a real LCD at job in few days. You means that the second sent byte is a problem only on proteus ?
On a classical I2C LCD the back light is connected to P3 of 8574.
How is connected the back light on yours ?
Thank you.
Yannick