Is a custom board for flashing ESP32 based prototypes normal needed?  - Page 1
Forum section: electronics / beginners

author: BryanToHire
author_rank: Newbie
timestamp: June 10, 2025, 04:30:11 am
content: Answered. Thank you.

author: jwet
author_rank: Frequent Contributor
timestamp: June 10, 2025, 04:45:09 am
content: A "custom" board for a few hundred bucks is reasonable, but why? All you need is an FTDI cable to give you TTL uart levels and use the bootloader as you say. These cables are plentiful and cheap. If you wanted to put an FTDI 232 on your board and have a USB plug, etc, at low volumes, it might be $5 for a chip and connector and some passives, but again why? You can even coax an old Arduino into the job- it has the FTDI part on board.I don't know if they're snowing you but they're not communicating. Buyer beware.Consultants have to make a living. If they have a nice solution for a competitive price or that they'll support and customize, you might want to use their stuff. These guys see a lot of flakes though and inexperienced entrepreneurs will pay top dollar.

author: BryanToHire
author_rank: Newbie
timestamp: June 10, 2025, 04:53:52 am
content: Hey Jwet, thank you.Yes, a custom board for that price seems reasonable but I also don't understand why.I will admit I also don't understand " All you need is an FTDI cable to give you TTL uart levels and use the bootloader as you say. "Is there not a common way to flashing firmware that would be suitable for both a prototype and production?Please correct me if I'm wrong as I justassumethere would be.It's my understanding that in production a JIG (like a bed of nails) is used to flash the firmware for each board.Again I don't really know too much about this. Just assuming there has to be some way to flash the firmware at home that doesn't involve adding an entire programming chip

author: jwet
author_rank: Frequent Contributor
timestamp: June 10, 2025, 05:31:36 am
content: The ESP32 has UART bootloader so all you need is a serial port to connect. Google around a bit- the ESP32 is used everywhere and is really easy to talk to.Here are a couple of links that I found with a quick search-https://electronics.stackexchange.com/questions/448187/esp32-with-ftdi-programmervideohttps://www.google.com/search?q=program+an+esp32+with+ftdi&rlz=1C1PRFI_enUS871US871&oq=&gs_lcrp=EgZjaHJvbWUqCQgAECMYJxjqAjIJCAAQIxgnGOoCMgkIARAjGCcY6gIyCQgCECMYJxjqAjIJCAMQIxgnGOoCMgkIBBAjGCcY6gIyCQgFECMYJxjqAjIMCAYQIxgnGOoCGLQEMgkIBxAjGCcY6gLSAQoxMjg1NTFqMGo3qAIIsAIB8QWQt9L3CXnLnw&sourceid=chrome&ie=UTF-8#fpstate=ive&vld=cid:6ca34fef,vid:lVRYdDcngCg,st:0

author: darkspr1te
author_rank: Frequent Contributor
timestamp: June 10, 2025, 09:10:44 am
content: It is very common on production devices to have the the pins for programming (tx,rx,boot mode, power, ground) broken out to a pin header(or holes) for quick programming , One designer i knew programmed one esp32 to program other esp32's with the new firmware and test routine.it went like this, A esp32 Programmer put a small bootloader on the target device, that would then OTA update from the wifi AP/server to a test package which when complete would set a flag, reboot and then the ota would flash with final production firmware. it took about 1 minute to complete per unit, he later sped this up by 3d printing a holding jig that would do test+final program automatically and eject the unit when complete , if a device failed it would light a red led, if it passed it was ejected it also ment the operator did not need special training, failed unit went into another tray for further testing and production checks. I dont think he sank more than $400 into this including the 3d printer and custom pcb for the jig +wiring.i've included a picture of a commercial product that exposes the programming header, i would assume they have a bed of nails jig they insert it into and apon connection it's programmed.Building your own jig is quite easy these days with 3d printing services and cheap pcb's , designing them how ever is not as easy :-)darkspr1te