Tab5 Power up sequence
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I have 2 Tab5 which I am powering through the Port A I2C connector. They won't power up when power cycled. IF I connect the USB C to aa hub, wait a few seconds, they then power up and stayed powered up. I have previously powered Tough boards through the I2C and it all worked fine.
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Hello @scroggyg
M5Tab5 port A is powered through a switch (U26) which when turned on lets
SYS_INT5Vthrough toSYS_EXT5VO. The switch is enabled viaEXT5V_ENcoming from one of the port expanders (U6).In other words, M5Tab5 cannot be turned on via port A as initially the switch is off.
See schematic here and/or the backside of M5Tab5.
Thanks
Felix -
I assume then the correct way to do this would be to use ExtPort2 and connect up to 12V through HVIN?
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I was wondering about the power-up sequence for the TAB5, and your breakdown really helped clarify things. Especially the part about the 3.3V rail timing—super useful detail.
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I have now bought both the PWRCAN and the Commu modules, neither apply power to SYSVIN or they do generate 5V on pin 28, which needs to be switched. I am using the TAB5 on a UK double gang plate with a 3D printed Bezel, you can't plug anything into the sides, as they would get removed.
It isn't practical to use the ExtPort2, as I would need to create a custom PCB to connect between the fine pitch fines to add a robust connector, are there any other options to power the TAB5 from behind?
Is there a Comms module ( I what to talk between 2 TAB5s over RS485) with a connector I can power the TAB5 from?
Thanks -
Hello @scroggyg
well, I think it shouldn't be too difficult to modify the PwrCAN module to provide power to SYSVIN.
BTW: the PwrCAN module schematic uses the label
HPWRon the connectors and the same label is on the M5Bus. Have you actually measured theHPWRpins of the M5Bus of the PwrCAN module? Maybe they are already connected?Note: I cannot verify this myself as I do not have a PwrCAN module.
Thanks
Felix
