HDMI is freezing with HD44780 LCD is connected via MCP23017 - Raspberry Pi Forums


hi there,

have non-explainable issue raspberry pi 2 model b somehow related hd44780 16x2 lcd display connected via mcp23017-e/sp expander on i2c interface.

once have lcd display connected, raspberry hdmi output gets frozen in couple of hours. @ time, when hdmi freezes, lcd continue working or show garbage on screen. once hdmi output got frozen, raspberry not gracefully rebooted. need plug power out restart it. however, else works fine besides hdmi , reboot.

behaviour not depend whether have adafruit touch screen connected or tv-set (it samsung in case). means, hdmi output freezes, not end-device.

lcd powered 5v, while mcp23017 powered 3.3v

know might issue? how pi working both lcd on mcp23017 without freezing hdmi?

regards,
victor

nakvic wrote:hi there,
have non-explainable issue raspberry pi 2 model b somehow related hd44780 16x2 lcd display connected via mcp23017-e/sp expander on i2c interface.
once have lcd display connected, raspberry hdmi output gets frozen in couple of hours. @ time, when hdmi freezes, lcd continue working or show garbage on screen. once hdmi output got frozen, raspberry not gracefully rebooted. need plug power out restart it. however, else works fine besides hdmi , reboot.
behaviour not depend whether have adafruit touch screen connected or tv-set (it samsung in case). means, hdmi output freezes, not end-device.
lcd powered 5v, while mcp23017 powered 3.3v
know might issue? how pi working both lcd on mcp23017 without freezing hdmi?
regards,
victor
whilst cannot sure "the lcd powered 5v, while mcp23017 powered 3.3v" related issue, things differently, powering mcp23017 5v (and using level shifters, which, in different circuit**, wasn't absolutely necessary) shown here:
http://www.cpmspectrepi.webspace.virgin ... allcd.html
(and that's driving 2 lcd displays).
trev.
** "slice of pi/o" approach:
http://www.cpmspectrepi.webspace.virgin ... ofpio.html


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