ESP8266 Community Forum

- Fri Apr 29, 2016 2:04 am #46443 Hi forks,

I am starting a project from bare metal using ESP8266 chip. The pcb, soldering is completed. I am using arduino blink example for testing the board. I got problem when flash esp8266 chip. It's can't flash. I power up the board and check GPIO0's voltage. It is 1.87V even I pullup with 10KOhm. GPIO2 is Hi and GPIO15 is low
Can anyone has an idea why?

I attach the schematic below

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- Fri Jun 10, 2016 6:06 am #48927 Hi tuongpv,

I've same issue on my custom board, do you solved the problem?

- Sun Jun 19, 2016 9:37 am #49426

Hi tuongpv,

I've same issue on my custom board, do you solved the problem?

Hi LashaD,

I solved my problem. The issui is i don't use 220Ohm bwt SDIO_CLK and CLK (of W25Q80DV). I cut the wire and solder a 220 Ohm, it runs Ok as well.
I hope this help.
Email me : phamtuongbk999[at]gmail[dot]com if u have further discuss

- Sun Jun 19, 2016 10:34 am #49428 Hi tuongpv,

Good idea on the design, I had a similar problem recently.
Things to check,

Supply voltage, sometimes under load (resistors, voltage dividers etc) can drop below it's brown-out voltage so won't boot.

Suggest removing C35, not really necessary, switch debounce wouldn't cause an issue at this point in the boot process.

I recommend, if I may, supplying the board with 5 volts and using a voltage regulator 3.3v to supply the esp8266 circuit, take a look at a free sample of MCP1700_3.3v regulator from microchip.com. I've used these with many esp8266_01s with success.

Best wishes and good luck in your endeavours.

Why is it that the more I learn, the more I'm aware of how little I know ?