Msp430 strange phenomenon

qinkaiabc

Msp430 strange phenomenon [Copy link]

I have replied to this before. I did not press the key, but it lit up when I brought my hand close to it.

wangfuchong

Did your hand touch the board? Did your hand touch the board?

qinkaiabc

Touched, not pressed

wangfuchong

Can you post the code? Especially the one related to the LED IO? Also, do you still have this problem when you use battery power? Try wearing shoes made of different materials? Does your computer's 220V power supply have a ground wire? If not, put a wire on the shell and step on it. Try changing the direction of your 220 power plug?

qinkaiabc

The code is a simple keystroke program. #include
void main(void) { WDTCTL = WDTPW + WDTHOLD; P1DIR |= BIT0+BIT6; P1OUT &=~BIT0+BIT6; P1IES |= BIT3; P1IE |= BIT3; P1IFG &=~BIT3; _BIS_SR(LPM4_bits + GIE); } #pragma vector=PORT1_VECTOR __interrupt void port(void) { P1OUT ^=BIT0+BIT6; P1IFG &=~BIT3; }

wangfuchong

Are you using the new version of LaunchPad or the old version? The new version does not have a pull-up resistor. If it is a new version, do you need to turn on the pull-up resistor in the software? Is this sentence necessary? ： P1IREN |= BIT3;

qinkaiabc

Well, that's it.

499362154

There is no pull-up or pull-down setting, it is the static electricity that is causing the problem: hug: When the MSP430 MCU IO port is used to detect high and low levels, no external pull-up or pull-down is required, because it has internal pull-up and pull-down. When used for high and low level detection, you need to turn on the pull-up or pull-down. If the effective state is high, you need to configure REN to enable the pull-up, and configure OUT to 0, that is, set it to pull-down. If the effective state is low, you need to configure REN to enable, and OUT bit 1, that is, set it to pull-up. If the internal pull-up is not turned on, the IO may appear in an unfixed state. For example, when the IO is input high, the external input is removed, but the IO register is still high. Note: The situation here is that after the IO is input high, the external input is withdrawn, but the IO register IN still remains high, but after the voltage is measured with a multimeter, the IO becomes 0. The reason for this situation is that a 3K resistor and a 100nf capacitor are connected in series to the ground of the IO, and the external input is added to the connection between the resistor and the capacitor. It should be that when external input is applied, the capacitor is charged, and the capacitor maintains the voltage after the external input is removed.

qinkaiabc

Thanks:)

在路上的旁观者

Learned

fghdzb

It should be that the IO port pull-up and pull-down are not done properly.

an736007364

Just like mine, P1.3 will light up when you touch it.

qinkaiabc

Add pull-up resistor

qinkaiabc

Internal pull-up, P1REN = P1.3; P1OUT |= P1.3;

qinkaiabc

Internal pull-up, P1REN = P1.3; P1OUT |= P1.3;

cyljs

499362154 Published on 2013-3-9 11:13 There is no pull-up or pull-down setting. It is static electricity that is causing the problem. When the MSP430 microcontroller IO port is used to detect high and low levels, no external pull-up or pull-down is required. ...

{:1_113:} Great! I didn't know about this and never paid attention to it. Thank you.

落叶的根藤

The problem of human body static electricity can be avoided by setting it up or down.