ESP32 PICO kit V4 manual RESET required

[tolo69]

Hi all,
I'm using ESP32 PICO kit V4. After flashing the SW starts execution properly. But after normal power ON, the SW doesn't start automaticly. I have to press the RESET (EN) button. How can I activate the automatic RESET after power ON ?

[kolban]

What (if anything) is logged to the serial output of your device when you boot it?

[tolo69]

After pressing RESET (EN) the Serial Output logs the following:

rst:0x1 (POWERON_RESET),boot:0x13 (SPI_FAST_FLASH_BOOT)
configsip: 188777542, SPIWP:0xee
clk_drv:0x00,q_drv:0x00,d_drv:0x00,cs0_drv:0x00,hd_drv:0x00,wp_drv:0x00
mode:DIO, clock div:1
load:0x3fff0018,len:4
load:0x3fff001c,len:956
load:0x40078000,len:0
load:0x40078000,len:11904
entry 0x40078a3c

[freemovers]

Hi, did you ever find a solution for this issue. I noticed the same behavior on the ESP32-PICO-KIT.

[freemovers]

I found a solution. On other ESP32 boards there is a pull-up resistor on the EN and IO0. The EN pin on the ESP32-PICO-KIT has this pull up resistor: https://dl.espressif.com/dl/schematics/ ... ematic.pdf.
The IO0 is missing this resistor and needs to be added. I didn't have a 10K resistor, but a 7.5K worked fine for me (see attached the solution, fortunately 3.3V is next to IO0.

WIN_20180430_19_47_43_Pro.jpg (243.85 KiB) Viewed 13844 times

[tolo69]

Thanks, for the hint. I can confirm, that this is the solution: I used a 10k resistor and it works for me too

[burgersonbrioche]

I am developing devices using the esp32-pico and started out with a 1uf capacitor tied to ground on EN and IO0. I was expreiencing the same issues. I switched out the 1uf capacitor on the EN pin for a 10uf capacitor and it started booting up the firmware no problem. I am hypothesizing that the larger capacitor on the EN pin takes longer to charge than the smaller one on IO0 thus making the EN pin go HIGH after IO0 as per the boot sequence. Any thoughts on this?