I am new to electronics and have recently got an ESP32-WROOM 30pin Development Board (https://randomnerdtutorials.com/getting-started-with-esp32/).
I am wondering if I can power other sensors through the board? If so what pin would I use?
I initially thought that the 3V3 pin was a 'power out' pin but upon reading some forums it seems like that is not the case. I am a bit confused as to what the difference between the Vin and 3V3 pin is
2 Answers 2
You can use the 3V3 pin to power other devices, but the current is limited.
Vin is the 5V from USB. This can also be used to power the board when USB is not connected.
What sensors did you want to power?
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\$\begingroup\$ One of the sensors is this [link] (au.element14.com/vishay/tsop98638/ir-receiver-24m-38khz-agc6-th/…). I also want to power [link] (jaycar.com.au/arduino-compatible-pir-motion-detector-module/p/…) but that requires 5V. Am I correct in thinking that I can use this breakout board [link] (core-electronics.com.au/usb-micro-b-breakout-board.html) to power the ESP32 through the Vin and to power the motion sensor? \$\endgroup\$Daniel– Daniel2021年12月22日 06:31:09 +00:00Commented Dec 22, 2021 at 6:31
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\$\begingroup\$ Those sensors are low current so I don’t see a problem. I’m not sure why you’d need a USB breakout board as your esp32 does that already. \$\endgroup\$Kartman– Kartman2021年12月22日 10:37:32 +00:00Commented Dec 22, 2021 at 10:37
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These ESP32 modules include a diode between USB +5V and internal +5V on the "5V" pin. This is to avoid sending power into the PC's USB port. So if your device is USB-powered, you can absolutely use the "+5V" pin to power your 5V sensors, however due to the diode it will be closer to 4.5V.
Your PIR sensor has a 3V3 LDO, so it probably runs on 3V3 internally. Due to the LDO it'll run fine on 4.5V instead of 5V, so no trouble. It also has 3V3 outputs, so it won't conflict with ESP32 IO voltage.
The 3V3 output is just the output of the LDO on your ESP32 module, you can use it to power your 3V3 sensors, like the TSOP that requires 3V3. You can use the RC filter shown on datasheet page 2 to reduce power supply noise.
Note the LDO on ESP32 boards is usually an AMS1117, which is garbage, so don't use more than a few tens of mA. If the ESP32 board has only ceramic caps, note AMS1117 isn't supposed to work with that. If there are tantalum caps, that'll probably work. I'd recommend placing a 100μF cap (or more) between the 3V3 pin and GND to help. If your ESP32 complains about brownouts on the serial console while crashing (like pretty much all of mine did occasionally), just replace with a real LDO, like LDL1117.