EN (Reset) Pin on some ESP32-C3-Mini-1-N4 modules does nothing

[GerryBriggs]

Schematic with secret parts blurred out

sm1_schematic_in_png_format2.png (165.23 KiB) Viewed 1380 times

What's the deal with GPIO2 ? Sorry I didnt know there was a GPIO2 requirement as well.

Here is the schematic - at least the parts that I can show. Nothing weird about the circuit. I can try again to look for ripple on the Vcc line but it looked amazingly clean and teh voltmeter didnt flinch when I hit reset. not even a movement by .1 volt.

The LiPo is 1000 mAh and I've used this LiPo on other ESP32C3 circuits and it worked perfectly.

I agree the 6 mA is suspicious

[GerryBriggs]

Alright so I took a dremmel tool and obliterated one line going to GPIO2 just in case it was pulling it down in voltage at all, since the technical reference manual also specifies that GPIO2 must be high for any kind of boot. Did that. Checked with the voltmeter. Perfect 3.3v on GPIO2, 3.3V on GPIO8, and 0v on GPIO9.

Still the same problem 6mA

[GerryBriggs]

You got me thinking about the boot problem - I dont have an oscilloscope handy, however I did stick a giant 2200 uF electrolytic capacitor between 3v3 and GND. Thinking that might stabilize the voltage just in case there was a problem on the regulator out put ..... annnnnd ... exact same problem. 6 mA

[GerryBriggs]

Added a 0.5 ohm shunt before the Vcc input of the ESP32C3 module

20240820_151737.jpg (2.01 MiB) Viewed 1180 times

I put in a little 0.5 ohm shunt right before the via that goes up to the Vcc pin of the ESP32C3 module. A little stack of 2 ohm resistors.

Last night I was only measuring the input to the regulator, but now measuring directly by using the new improvised shunt.

The measured current going into the module is 7.9 milliamps when EN at 3.3V, and the current is 0.0 milliamps when EN is brought to 0 (the reset condition). Then the input current returns to 7.9 milliamps when EN brought back up to 3.3 V.

[GerryBriggs]

Fixed and solved.

The 2 problems I had which compounded the problem were :

1. I didnt know that some modules do not come preprogrammed with any kind of default code - I was expecting a WiFi access point named Espressif but got none. Some modules just come with "Invalid Header 0xFFFFFFFF" and they absolutely have to be programmed by UART (or USB) before they can function.

2. I had a bad FTDI cable pin that only turned bad in the interval between going from my usual ESP32C3 device (which worked) to the new one that was being tested.

The pin has been fixed (a bad wire joint) and I can say that the correct current to expect going directly into the module is exactly 7.9 milliamps at 3.3 V for Vcc. This corresponds to the "Invalid Header 0xFFFFFFFF" which will scroll repeatedly on TX. When reset with GPIO9 at 0v, the module accepts new code per normal.

What did I learn? There are some modules that ship with default code (what I was used to) which causes an Espressif AP for OTA programming, and then other modules that do not have any code at all in the flash. And they can be shipped by the same CM (in this case JLCPCB).

[ESP_Sprite]

Good to hear you've solved it, and thanks for sharing what the issue was!