Overview:
- Dedicated power management subsystem supporting Ultra–Low Power processing for long battery life use cases.
- Sensor Hub use case to demonstrate deep sleep and wake up transitions while consuming very low power.
- Evaluation Kit enabling Power Measurement and Tools (GUI and Command line)
System operation
The i.MX8ULP features the energy flex architecture which consists of the Application domain, Flex domain and Real Time domain. Different power modes can be achieved by the dedicated power management system to optimize the power consumption.
In the Sensor Hub use case, the Application and Flex domain are shutdown, while preserving the Real Time domain only.
After the boots up, The Linux suspends(A-core) and M33(M-core) enters deep sleep mode and the screen turns off. When we tilt the board(simulate wrist lifting), the gyro sensor LSM6DSO will send an interrupt signal to M33, M33 will wake up and acquire the sensor data and display it on the screen. After 3 seconds, the system enters deep sleep mode again.
Software Architecture
Hardware required
- i.MX8ULP EVK board
- WaveShare1.28inch LCD Module
- LSM6DSO sensor (on board)
- MPL3115 sensor (on board)
Software Required
- M33 image built from the GitHub: https://github.com/nxp-imx-support/imx8ulp-cm33-usecase/blob/sensorhub_sync_github/README.md
Hardware Changes to the EVK:
EVK:
For the hardware rework, we first need to weld some rows of pins on :
J23,J26 on the board back, but we leave the longer pin in front
J21 on the board back
Another hardware rework, we need to remove R161 R167, and connect a 0 ohm resistor at R160, R166(Or short circuited)
Panel:
Pin Mapping
|
OLED PIN |
i.MX8ULP PIN |
BOARD PIN position |
|
VCC |
3.3V |
4th pin in J22 |
|
GND |
GND |
6th pin in J22 |
|
DIN |
PTA21 |
7th pin in J21 |
|
CLK |
PTA22 |
6th pin in J21 |
|
CS |
PTA15 |
1st pin in J23 |
|
DC |
PTA6 |
6th pin in J23 |
|
RST |
PTA24 |
5th pin in J23 |
|
BL |
PTA18 |
4th pin in J23 |
Instructions to run the demo:
- Power on the board.
- After Linux boots up, set Linux to suspend mode on the A35 console: "echo mem > /sys/power/state"
- Press any key on the Cortex M33 console to start the Sensor Hub application. The system will then enter the deep sleep mode.
- When the user tilts/lifts the board, the system will wake up and retrieve the data from the onboard sensors to display on the screen.
- After 3 seconds, the system enters deep sleep mode again.
Demo video:
In this demo, The Sensor Hub leverages the high performance, rich peripherals and ultra low power of the i.MX8ULP. The power consumption is around 1.1mWatt in standby mode. The system also achieves fast wakeup from the standby mode.