Frequently Asked Questions about Lingdongwei MM32F103 MCU

火辣西米秀

Frequently Asked Questions about Lingdongwei MM32F103 MCU [Copy link]

 

The MM32F103 series of Lingdongwei products use a 32-bit microcontroller with a high-performance core M3, with a typical operating frequency of up to 144MHZ, built-in high-speed memory, and a rich set of enhanced I/O ports and peripherals connected to the external bus. Five packaging forms are available, including LQFP100, LQFP64, LQFP48, LQFP32 and QFN32. Depending on the packaging form, the peripheral configuration in the device is different. This product is suitable for use in motor drive and application control, medical and handheld equipment, industrial applications, and alarm systems.

SPI

1. Which modes does SPI support?

According to the transmission direction

• Full-duplex mode, sending and receiving data at the same time, enabling TX and RX at the same time;
• Half-duplex, read and write in different time periods, DISABLE RX when ENABLE TX, DISABLE TX when ENABLE RX;
• By sampling timing
• Mode 0, the clock is low when idle, and the first clock edge is sampled;
• Mode 1, the clock is low when idle, and the second clock edge is sampled;
• Mode 2, the clock is high when idle, and the first clock edge is sampled;
• Mode 3, the clock is high when idle, and the second clock edge is sampled;

2. What are the reasons for abnormal SPI host communication?

Common causes:

Incorrect configuration means no clock output;
incorrect mode configuration means the sampling point is inconsistent with the expectation (SPI_CCTL bit0 = 0 is the second clock edge sampling);
the speed configuration is too fast, which means abnormal waveform;
the data bit configuration is inconsistent with the device, which means the number of CLKs is incorrect.
Incorrect CS signal means the CS signal does not correspond to the device timing;
What are the requirements for Vbat power supply access?
If there is no external battery in the application, it is recommended that VBAT be connected to VDD through a 100nF ceramic capacitor externally. If the external battery is connected, it is recommended to connect a low voltage drop diode between the external VBAT and the power supply to ensure that it is not damaged. If there is no external battery, VBAT needs to be powered even if the RTC function is not used;

Possible causes of KEIL routine compilation failure

Common causes:

The compatible package of Keil4 is not installed. The software name is: MDKCM516_legacySupportMDK4 (most problems)
The Keil project file is moved, resulting in the inability to find the file with the relative path.
The program is too large and exceeds the FLASH or SRAM capacity.

Solution

For questions 1 and 2, connect BOOT0 and BOOT1 to high level, reset or power on again, and then read the ID. If the ID can be read, erase the program in this mode, and then connect BOOT0 and BOOT1 to low level, then the ID can be read.

The KEIL program was compiled successfully, but the download failed.

Common causes:

The hardware circuit is not connected properly. Check whether the debug tool is connected to the JTAG or SWD in the board and whether the chip IDCODE can be read.
If the debug tool can read the chip ID but cannot download, the reason is that the Description model is not selected. The specific configuration selection is shown in the figure below.

External high-speed clock connection

The external passive crystal oscillator circuit is shown in the figure below. The two pins of the crystal oscillator are connected to a capacitor of about 22pf and a 1M feedback resistor. Because there is no integrated feedback resistor inside the chip, a 1M ohm resistor must be connected to ensure that the XTAL starts oscillating.

Common causes of external clock abnormality

When running a program, an external high-speed clock is usually used as the system clock source. Sometimes during debugging, the system clock is abnormal, causing the program to stop running. The following are some possible reasons:

• The external crystal oscillator has no feedback resistor, resulting in no stable external clock input;
• External crystal range 8~24MHz;
• There is a short circuit between the crystal oscillator and the chip pins;
• The crystal oscillator quality problem causes abnormal oscillation;
• Chip system clock configuration process error, etc.

sunlei11223344

I hope China can produce M7 core CPUs, such as STMicroelectronics' STM32H7 series

18566202629

Now there is a dual-core M7 MCU, the main frequency can run at 800MHZ