ESP32 has 18 RTC GPIOs and 10 touchpads, which can all be configured as the wake-up source to wake up the chip from deep sleep.
- Purpose: measure the current consumptions of ESP32 in Deep_sleep mode, under different wake-up setups;
- Tool: ESP32_ULP_EB V1 evaluation board. For details on how to use this board and complete configuation, please refer to User Guide to ESP32_ULP_EB;
- Scope: The current consumption of all the RTC GPIOs and touchpads of ESP32 are measured in this test, except for RTC GPIO_37 and RTC GPIO_38.
Notes: GPIO_37 and GPIO_38 are not tested here, becuase these two pads are not led out to the pin header of the board.
External events can trigger level signals of the RTC GPIO, which has been configured as the wake-up source of the chip, and wake up the chip from deep sleep.
Wake-up source
-
EXT(0): wake up the chip when a specific GPIO pad, which has been configured as the wake-up source of the chip, meets certain requirement regarding electrical level. This GPIO can be configured as "high-level" triggered or "low-level" triggered;
-
EXT(1): wake up the chip when a set of specified GPIO pads, which have been configured as the wake-up sources of the chip, all meet certain requirements regarding electrical level. One GPIO can also be seen as a set of specified GPIOs (In this case, EXT(1) has no difference with EXT(0)).
Configuration
- Set a RTC GPIO as the wake-up source of the chip, and configure it to input floating mode;
- Resistors:
- when the GPIO is configured as high-level triggered, a 10 kΩ pull-down resistor should be used;
- when the GPIO is configured as low-level triggered, a 10 kΩ pull-up resistor should be used;
Notes: To achieve lower power consumption, external resistors, instead of internal ones, are recommanded in this case.
Test Result
- Wake-up source: EXT(0)
| GPIO NUM | Low-level triggerred | High-level triggered |
|---|---|---|
| GPIO_0 | 6.3 uA | 6.2 uA |
| GPIO_2 | 6.3 uA | 6.2 uA |
| GPIO_4 | 6.4 uA | 6.2 uA |
| GPIO_12 | 6.4 uA | 6.4 uA |
| GPIO_13 | 6.3 uA | 6.3 uA |
| GPIO_14 | 6.3 uA | 6.3 uA |
| GPIO_15 | 6.4 uA | 6.4 uA |
| GPIO_25 | 6.3 uA | 6.5 uA |
| GPIO_26 | 6.6 uA | 6.3 uA |
| GPIO_27 | 6.4 uA | 6.4 uA |
| GPIO_32 | 6.4 uA | 6.4 uA |
| GPIO_33 | 6.4 uA | 6.4 uA |
| GPIO_34 | 6.4 uA | 6.2 uA |
| GPIO_35 | 6.4 uA | 6.3 uA |
| GPIO_36 | 6.4 uA | 6.3 uA |
| GPIO_37 | \ | \ |
| GPIO_38 | \ | \ |
| GPIO_39 | 6.4 uA | 6.3 uA |
- Wake-up source: EXT(1)
| GPIO NUM | Low-level triggered | High-level triggered |
|---|---|---|
| GPIO_0 | 5.2 uA | 5.3 uA |
| GPIO_2 | 5.2 uA | 5.2 uA |
| GPIO_4 | 5.2 uA | 5.2 uA |
| GPIO_12 | 5.2 uA | 5.3 uA |
| GPIO_13 | 5.3 uA | 5.2 uA |
| GPIO_14 | 5.3 uA | 5.3 uA |
| GPIO_15 | 5.3 uA | 5.2 uA |
| GPIO_25 | 5.2 uA | 5.3 uA |
| GPIO_26 | 5.3 uA | 5.2 uA |
| GPIO_27 | 5.3 uA | 5.3 uA |
| GPIO_32 | 5.3 uA | 5.3 uA |
| GPIO_33 | 5.3 uA | 5.3 uA |
| GPIO_34 | 5.3 uA | 5.7 uA |
| GPIO_35 | 5.3 uA | 5.7 uA |
| GPIO_36 | 5.3 uA | 5.3 uA |
| GPIO_37 | \ | \ |
| GPIO_38 | \ | \ |
| GPIO_39 | 5.4 uA | 5.5 uA |
Conclusion
- The current consumptions of the chip are basically the same and extremely low during the deep sleep, when different RTC GPIOs are configured as the wake-up sources；
- The current consumptions of the chip in EXT1 mode are about 1 uA lower than that in EXT0 mode.
| Pad Num | Current |
|---|---|
| Pad0 (GPIO_4) | 37.3 uA |
| Pad1 (GPIO_0) | 35.7 uA |
| Pad2 (GPIO_2) | 36.6 uA |
| Pad3 (GPIO_15) | 35.6 uA |
| Pad4 (GPIO_13) | 36.5 uA |
| Pad5 (GPIO_12) | 36.1 uA |
| Pad6 (GPIO_14) | 36.7 uA |
| Pad7 (GPIO_27) | 35.7 uA |
| Pad8 (GPIO_33) | 36.7 uA |
| Pad9 (GPIO_32) | 36.3 uA |
Touchpad can be enabled as the wake-up source to wake up the chip from deep sleep.
Configuration
- Set a touchpad as the wake-up source of the chip, and initialize this pad;
- Set up the touchpad's trigger threshold.
Test Result
- Wake-up source: touchpad
| Pad Num | Current |
|---|---|
| Pad0 (GPIO_4) | 37.3 uA |
| Pad1 (GPIO_0) | 35.7 uA |
| Pad2 (GPIO_2) | 36.6 uA |
| Pad3 (GPIO_15) | 35.6 uA |
| Pad4 (GPIO_13) | 36.5 uA |
| Pad5 (GPIO_12) | 36.1 uA |
| Pad6 (GPIO_14) | 36.7 uA |
| Pad7 (GPIO_27) | 35.7 uA |
| Pad8 (GPIO_33) | 36.7 uA |
| Pad9 (GPIO_32) | 36.3 uA |
Notes: touch_pad_set_meas_time can be used to adjust the charging/discharging cycle and the detection period of the touch sensor accordingly, so as to optimize the response time and achieve even lower power consumption.