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BV4614 - impossible to change device address from raspberrypi both for serial and I2C interfaces

Posted by fab 
Hi to everyone

I bought 3 7-segment LED displays with the ambition to drive them by RASPBERRY PI leveraging on etiher I2C interface or SERIAL (SV3).

All the temptative I did to change the I2C or SERIAL address of the displays failed.
In both cases I write into the EPROM ADDRESSES 1 (0x01), 14 (0x0e), 250 (0xfa) a new address (i.e 100) rather than the current one (98 for serial and 49 for I2C since it used the 7 bit address notation). The write operation was successful since I try to read the relevant addresses and they contained exactly the wanted values but after a soft reset ("C" command for serial and 0x95 for I2C) they go back to their initial values (98 or 49)

Few more infos on the temptatives i did:
- to change the address i connected the display once at time
- for serial interface I leveraged the python library SERIAL. I used write() and read() commands
- for I2C interface I leveraged on the I2Ctools. Commands used form I2C tools were : i2cdetect, i2cset, i2cget. eprom commands send by i2cset were 0x90 (read) 0x91 (write) 0x95 (reset)
- i feed them with 5v power supply (for the I2C on raspberry i use a level shifter to bring the SDA/SCL signal level up to 5v). With serial i did not use any level shifter but i tried also to swap the power supply to 3.3 v with no changes on results... (displays were just more dimmed)
- all remaining commands (i.e setting up a number or a byte or the brightness on a specific digit) were working fine whatever interface i used
- every other I2C device i had on my I2C bus works well (i have the pullup resistor there)

any help will be appreciated, thx
I can help, there is a problem when using more then one BV4614 with firmware version 1.2, which is probably what you have. It needs updating which I can do. Can you contact me: jim at byvac.com to make the arrangements.

*** This applies only to devices with 1.2 or earlier firmware, there is a workround and that is to connect the reset pin (4) on the serial connector to ground. This will prevent the device from reverting back to the default address. Of course this only matters when more than one device is in use. ***


Edited 1 time(s). Last edit at 11/05/2013 04:42PM by jimeer.
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