Why the GD32F103ZET6 Won't Enter Sleep Mode and How to Fix It

Why the GD32F103ZET6 Won't Enter Sleep Mode and How to Fix It

The GD32F103ZET6 microcontroller is a popular chip used in embedded systems, and like many microcontrollers, it has low- Power modes such as Sleep Mode to help reduce power consumption. However, sometimes the chip may fail to enter Sleep Mode as expected. In this guide, we'll analyze the potential causes of this issue and provide a step-by-step solution to help you resolve it.

Potential Causes for the Issue

Incorrect Sleep Mode Configuration One of the most common reasons the GD32F103ZET6 won’t enter Sleep Mode is improper configuration of the microcontroller's power management settings. The chip has different low-power modes like Sleep Mode, Stop Mode, and Standby Mode, and each mode has specific configuration requirements.

Peripheral or Interrupt Activity The microcontroller might be unable to enter Sleep Mode if active peripherals or interrupts are preventing it. Peripherals such as timers, ADCs, or UARTs that are continuously running can keep the chip from entering a low-power state.

Interrupt Flags and Masking If the interrupt flags are not cleared or if interrupt masking is not configured correctly, the chip may not be able to enter Sleep Mode. Interrupt-driven peripherals might be continuously requesting attention from the processor, thus keeping it in active mode.

System Clock Configuration The clock configuration could also interfere with Sleep Mode. If the system clock or certain peripheral clocks are not disabled correctly, the chip might not be able to transition into a low-power mode.

Software Bugs or Logic Errors Sometimes, the issue may be related to software logic, such as forgotten commands to enable the sleep mode or errors in the condition checks for entering sleep mode. If your program doesn't correctly trigger the sleep mode or checks the wrong condition, the system may fail to enter sleep mode.

Troubleshooting and Fixing the Problem

Here’s a step-by-step guide to fix the issue:

Step 1: Verify Sleep Mode Configuration Check the PWR (Power Control) Register: The GD32F103ZET6 uses the PWR register to configure power modes. Make sure that you are setting the SLEEPDEEP bit and the SLEEPONEXIT bit in the correct manner.

SLEEPDEEP sets the deep sleep mode for the MCU.

SLEEPONEXIT ensures the MCU enters sleep mode when the CPU exits an ISR (Interrupt Service Routine).

Example Code Snippet:

PWR->CR |= PWR_CR_SLEEPMODE; // Enable Sleep Mode SCB->SCR |= SCB_SCR_SLEEPDEEP_Msk; // Enable Deep Sleep Mode Ensure the Correct Low Power Mode is Chosen: The GD32F103ZET6 can enter several different low-power modes. Ensure you are using the correct one for your application (Sleep Mode vs. Stop Mode vs. Standby Mode). Sleep Mode is often the most appropriate when you want to reduce power but still allow peripherals to operate. Step 2: Check Active Peripherals

Disable Unnecessary Peripherals: Review all active peripherals in your application. Some peripherals, like timers, ADCs, or communication interface s (UART, SPI), may prevent the chip from entering Sleep Mode. If these peripherals are unnecessary at the moment, disable them.

Example Code Snippet:

// Disable Timer1 (as an example) TIM1->CR1 &= ~TIM_CR1_CEN; // Stop the Timer1

Check for Ongoing Interrupts: Interrupts may keep the system awake if they are constantly triggered. Make sure you disable or mask interrupts that are not necessary during the low-power mode.

Example Code Snippet:

__disable_irq(); // Disable all interrupts Step 3: Correct Interrupt and Flag Handling

Clear Pending Interrupt Flags: If an interrupt flag is pending and not cleared, it may prevent the MCU from entering Sleep Mode. Make sure that you handle interrupt flags properly by clearing them once they are handled.

Example Code Snippet:

// Clear interrupt flag for TIM1 TIM1->SR &= ~TIM_SR_UIF;

Mask Unnecessary Interrupts: Ensure that unnecessary interrupts are masked or disabled. For example, if you're not using an external interrupt, you should disable it to avoid interference with Sleep Mode.

Example Code Snippet:

EXTI->IMR &= ~EXTI_IMR_MR0; // Mask external interrupt 0 Step 4: Review the System Clock Configuration

Disable Unnecessary Clocks: Ensure that unnecessary system clocks are disabled when the chip is entering low-power mode. The MCU needs to be in a state where it’s not constantly powered by system or peripheral clocks.

Example Code Snippet:

RCC->APB2ENR &= ~RCC_APB2ENR_USART1EN; // Disable USART1 clock

Use Low-Speed Oscillator for Sleep Mode: If you are in Sleep Mode and need to keep some peripherals running, consider switching the system to a low-speed oscillator, such as the LSI (Low-Speed Internal oscillator), which can help reduce power consumption.

Example Code Snippet:

RCC->CSR |= RCC_CSR_LSION; // Enable LSI oscillator Step 5: Ensure Proper Software Logic

Verify Logic for Entering Sleep Mode: Double-check your software logic to ensure that you are correctly checking the conditions to enter Sleep Mode. Often, the MCU may fail to enter sleep mode because the condition or flag is not set correctly.

Example Code Snippet:

if (some_condition_is_met) { __WFI(); // Enter Sleep Mode using the "Wait For Interrupt" instruction }

Use __WFI() Instruction: The __WFI() (Wait For Interrupt) instruction tells the processor to enter a low-power state (Sleep Mode) until an interrupt is triggered. Make sure to call this instruction at the right place in your code.

Example Code Snippet:

__WFI(); // Enter Sleep Mode

Conclusion

By following these steps, you should be able to identify and fix the issue preventing your GD32F103ZET6 from entering Sleep Mode. Make sure to check your configuration settings, disable unnecessary peripherals, and manage interrupts properly. If the issue persists, reviewing your software flow and checking for hardware-related problems might be necessary. By carefully applying these solutions, you can efficiently manage power consumption and get your microcontroller to enter Sleep Mode as intended.