A simple pull-up and pull-down circuit causes the control chip to heat up!

燕园技术宅

A simple pull-up and pull-down circuit causes the control chip to heat up! [Copy link]

The problem is this, in order to manually set the input level state of some pins of the STM32F103 series microcontroller (statement: because a certain function is to be completed, it is randomly set by the peripheral circuit, so it cannot be set by modifying the program), the circuit is shown in the figure. Several pins of the microcontroller are configured as pull-up input mode, so I only solder 0 ohm resistors to ground some pins that need to be pulled to a low level, so that the input of the pin becomes a low level. As for the 3.3V end, it can be ignored. Because it is a pull-up input mode, this part of the circuit is basically not used. The circuit can achieve this function, that is, as long as the 0Ω resistor is soldered, the chip will heat up as soon as the power is turned on, and the microcontroller can work normally. I want to ask for help, what is the reason? The circuit is too large after the pull-up mode pin is grounded? ? ? It has been ruled out. As long as a small resistor of 0Ω or a few ohms is soldered, the chip will heat up, and other slightly larger resistance values will be fine. Another question is, without soldering any resistors, the voltage level of the PD0-PD7 pins is usually 3.3V, while the voltage level of the PD8-PD15 pins is usually 1.7V. What's going on?

littleshrimp

Remove the 0 ohm resistor and use the multimeter current range to measure the two ends of each resistor. Find the ones with the largest current and check whether the corresponding GPIO is configured correctly.

燕园技术宅

littleshrimp posted on 2019-3-23 21:26 Remove the 0 ohm resistor and use the current range of the multimeter to measure the two ends of each resistor. Find the ones with the largest current and check whether the corresponding GPIO is configured correctly.

I checked the program and found that they are all in pull-up mode GPIO_Mode_IPD. I measured the current and found a very strange phenomenon. As described in the question, the circuit is divided into two blocks, each with eight channels, and the functions are the same. When measuring the voltage, the voltage of each channel of the first block was pulled down to 3.3V, and the measured current was 560uA. However, the voltage of each channel of the other block was pulled up to 1.7V, and the measured current was zero (Figure 3 is the block with abnormal current).

燕园技术宅

littleshrimp posted on 2019-3-23 21:26 Remove the 0 ohm resistor and use the multimeter current range to measure the two ends of each resistor. Find the ones with the largest current and check whether the corresponding GPIO is configured correctly.

Found the problem. Several pins were configured repeatedly in other library files of the program.