Hi Michael, The warnings occur when Arduino IDE is set to display them. You can disable them here: menu File -> Preferences -> Settings tab -> Compiler warnings -> set to None. > 1. Is this the problem you are referring to? No. The problem is not related to compilation warnings and errors. The problem is that the uploaded software crashes when it writes to non-volatile memory or connects to wifi. When it crashes the ESP32 transmits a crash dump to the serial port and resets. These crashes don't occur with the October 2017 version. > 2. How can I install the October 2017 version of the ESP32 software? There's a link to the October 2017 version of Arduino Core for ESP32 at the start of this topic. It's basically a snapshot of the GitHub repository taken on 6th October 2017. This is not a special day, it's just the day we took the snapshot for installing the package. Installation should be the same as described on the GitHub page. You can read the .md files in the October 2017 version to be sure. > 3. Heating voltage problems (T3) We don't know the details about your problem with the heating voltage. In the past we experienced some problems with 2N7000 MOSFET transistors. Some of them do conduct a little bit without gate voltage applied (0 V). That was the case with some Chinese variants. The 2N7000's in the kit are from ON Semiconductor. Anyway, if the problem persists, you can try to replace T3.

Finally managed to upload the binaries. It's the same under Linux as in Windows. esptool.py --chip esp32 --port /dev/ttyUSB0 --baud 921600 --before default_reset --after hard_reset write_flash -z --flash_mode dio --flash_freq 80m --flash_size detect  0xe000 boot_app0.bin 0x1000 bootloader_qio.bin 0x10000 vfd_clock_wifi.ino.bin 0x8000 vfd_clock_wifi.ino.partitions.bin Still have a problem with the heating voltage (T3) but the clock is running fine. Thanks for reading.

salon du laboratoire Paris 1987 ou 88 Pour illustrer mes premiers dispenseurs  de la boratoire piloter par un Psion LZ programmé en OPL j'ai réaliser un piano-cocktail inspiré par le livre l'Ecume des jours de Boris Vian, ce fut un grand succés, j'ai gagné le prix de la meilleur utilisation par la société Psion -France avec cette application qui ne fut jamais commercialisé. le monde se réinvente toujours... JP  

Well, to be honest, dealing with the Arduino IDE is a pain in the a##. I am running Arduino UDE 1.8.5 on Ubuntu 16.04 and added the ESP32 DevModule like instructed on GitHub. Everything looks fine - all libraries loaded. When trying to compile I get approx. 70 lines like this: /home/mto/software-inst/arduino-1.8.5/vfd_clock_wifi/clock.ino: In function 'void Clock_Read(CMD_PROC*)': /home/mto/software-inst/arduino-1.8.5/vfd_clock_wifi/clock.ino:80:38: warning: ISO C++ forbids converting a string constant to 'char*' [-Wwrite-strings]      p->emit_str_fn(p,"Time not set",0); 1. Is this the problem you are referring to? 2. How can I install the October 2017 version of the ESP32 software? 3. As an alternative how can I upload the ready made binaries you provide?    There is a Windows how-to only... Appreciate your help on this. Michael

Side note. The above discussion does not account for any issues which may be caused by an imbalance in the stack caused by different end state capacities and voltages.  For non rechargable cells this is not likely to cause any significant problems but that is another discussion.