Customer requirement and making it happen
This hands-on test is coming with the true customer requirement. Customer designs the battery powered device with SLCD display and lowest power consumption is the key requirement. Customer considers the KL43 and wonder the power consumption data about RTC & SLCD modules. So there with below requirements about the test:
- Run the RTC and SLCD in the lowest possible power mode
- Display time at SLCD with [00:00] and update every minute via RTC interrupt
- One button shall turn on/off the SLCD display
- Measure the KL43 power consumption data
- KDS IDE with KSDK V2.0 software
According to above requirement, which low power mode should be selected? RTC and SLCD modules should work at this low power mode. From the KL43 reference manual table 7-2 [Module operation in low power modes] with below info:
5. In VLLS0 the only clocking option is from RTC_CLKIN.
7. End of Frame wakeup not supported in LLS and VLLSx.
RTC and SLCD modules could work at VLLS1 low power mode with Async operation. Using VLLS1 low power mode, the RTC and SLCD module clock could select OSC32KCLK with below clocking figure:
KL43 wake up from VLLS1 low power mode following wake up reset and the software will check the system reset status register to check what kind of reset happens and print related info. LLWU module is used as VLLS1 lower power mode wake up module with two wake up source, one is RTC Alarm interrupt, the other one is PTC3 (SW3). The Reset pin (SW2) also could wake up the VLLS1 low power mode.
Test environment introduction
Hardware platform using FRDM-KL43Z board with below feature:
- MKL43Z256VLLZ4 MCU (48 MHz, 256 KB flash memory, 32 KB RAM, 16 KB ROM
- Dual role USB interface with mini-B USB connector
- Four-digit segment LCD module
- Capacitive touch slider
- Ambient light sensor
- MMA8451Q accelerometer
- MAG3110 magnetometer
- 2 user push buttons
- Battery-ready, power-measurement access points
- Arduino R3 compatibility
Software platform bases on KSDK V2.0 for FRDM-KL43Z board, which could be downloaded from kex.nxp.com.
Attached demo software default path is: C:\Freescale\SDK_2.0_FRDM-KL43Z\boards\frdmkl43z
Test software code introduction
Below is the software flow chart:
- SLCD ON with power consumption 2.0uA
- SLCD OFF with power consumption 1.2uA