Thanks for that, useful info.
I'm not sure we have UVLO - that would mean insufficient input voltage to the ehtire chip. This has to be measured good prior to attempting the start up of the DCDC1 module. Power up of DCDC1 is the bit that is failing.
That is not to say that the screen is not borked or cracked (I can't see any crack and it failed in mid refresh), but the boot messages suggest something to do with the chip (possibly mistakenly, it's a dumb computer after all). I'm 90% sure the screen is good at the moment.
The data sheet says this (and much more):
Quote:
8.3 Feature Description
8.3.1 Wake-Up and Power-Up Sequencing
The power-up and power-down order and timing is defined by user register settings. The default settings support the E Ink Vizplex panel and typically do not need to be changed.
In SLEEP mode the TPS65185x is completely turned off, the I 2 C registers are reset, and the device does not accept any I 2 C transaction. Pull the WAKEUP pin high with the PWRUP pin low and the device enters STANDBY mode which enables the I 2 C interface. Write to the UPSEQ0 register to define the order in which the output rails are enabled at power-up and to the UPSEQ1 registers to define the power-up delays between rails. Finally, set the ACTIVE bit in the ENABLE register to 1 to execute the power-up sequence and bring up all power rails.
Alternatively pull the PWRUP pin high (rising edge).
After the ACTIVE bit has been set, the negative boost converter (VN) is powered up first, followed by the positive boost (VB). The positive boost enable is gated by the internal power-good signal of the negative boost. Once VB is in regulation, it issues an internal power-good signal and after delay time UDLY1 has expired, STROBE1 is
issued. The rail assigned to STROBE1 will power up next and after its power-good signal has been asserted and delay time UDLY2 has expired, STROBE2 is issued. The sequence continues until STROBE4 has occurred and the last rail has been enabled.
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So VB (our DCDC1 circuit) is powered up second after VN (DCDC2, should be -16V). I could try seeing if VN comes on and has the correct voltages, if they are wrong that might indicate a problem with the screen....