刚接触stm32，有许多不懂？
最近在弄stm32f429-discovery，adc单通道多路采集（非DMA），
我设置了8路PA0-PA7；通过USART1反馈回电压值；
在外面连了一个滑动变阻器，连得是stm32f429-discovery上的3V，万用表测得电压2.97V；
滑动 滑动变阻器，测试了PA0，PA1，PA5；
PA0数值从0.016左右到0.6左右变化
PA1数值从0.016左右到2.6左右变化，当滑动变阻器接近最大阻值时，数值突然跳到44左右；
PA5数值从0.016左右到55左右变化；

求解释呀？
adc配置函数： [mw_shl_code=c,true]#include "adc.h" #include "delay.h" #include "stm32_tpdata.h" void Adc_Init(void) { GPIO_InitTypeDef GPIO_InitStructure; ADC_CommonInitTypeDef ADC_CommonInitStructure; ADC_InitTypeDef ADC_InitStructure; RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE); RCC_APB2PeriphClockCmd(RCC_APB2Periph_ADC1, ENABLE); GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0|GPIO_Pin_1|GPIO_Pin_2|GPIO_Pin_3|GPIO_Pin_4|GPIO_Pin_5|GPIO_Pin_6|GPIO_Pin_7; GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AN; GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL ; GPIO_Init(GPIOA, &GPIO_InitStructure); RCC_APB2PeriphResetCmd(RCC_APB2Periph_ADC1,ENABLE); RCC_APB2PeriphResetCmd(RCC_APB2Periph_ADC1,DISABLE); ADC_CommonInitStructure.ADC_Mode = ADC_Mode_Independent; ADC_CommonInitStructure.ADC_TwoSamplingDelay = ADC_TwoSamplingDelay_5Cycles; ADC_CommonInitStructure.ADC_DMAAccessMode = ADC_DMAAccessMode_Disabled; ADC_CommonInitStructure.ADC_Prescaler = ADC_Prescaler_Div4; ADC_CommonInit(&ADC_CommonInitStructure); ADC_InitStructure.ADC_Resolution = ADC_Resolution_12b; ADC_InitStructure.ADC_ScanConvMode = DISABLE; ADC_InitStructure.ADC_ContinuousConvMode = DISABLE; ADC_InitStructure.ADC_ExternalTrigConvEdge = ADC_ExternalTrigConvEdge_None; ADC_InitStructure.ADC_DataAlign = ADC_DataAlign_Right; ADC_InitStructure.ADC_NbrOfConversion = 1; ADC_Init(ADC1, &ADC_InitStructure); ADC_Cmd(ADC1, ENABLE); } u16 Get_Adc(u8 ch) { ADC_RegularChannelConfig(ADC1, ch, 1, ADC_SampleTime_480Cycles ); ADC_SoftwareStartConv(ADC1); while(!ADC_GetFlagStatus(ADC1, ADC_FLAG_EOC )); return ADC_GetConversionValue(ADC1); } u16 Get_Adc_Average(u8 ch,u8 times) { u32 temp_val=0; u8 t; for(t=0;t<times;t++) { temp_val+=Get_Adc(ch); delay_ms(5); } return temp_val/times; } [/mw_shl_code] 主函数：
[mw_shl_code=c,true]#include "stm32f4xx.h" #include "spi_config.h" #include "usart_config.h" #include "delay.h" #include "adc.h" #include <stdio.h> int main(void) { int y=0; int qq; u16 adcx = 0; float temp; char buffer[7]; USART_Config(); Adc_Init(); USART_SendData(USART1,0xa0); while(USART_GetFlagStatus(USART1, USART_FLAG_TC) == RESET); while(1) { adcx=Get_Adc_Average(ADC_Channel_1,10); temp=(float)adcx*(3.3/4096); sprintf(buffer,"%f",temp); for(y=0;y<7;y++) { USART_SendData(USART1,buffer[y]); while(USART_GetFlagStatus(USART1, USART_FLAG_TC) == RESET); } USART_SendData(USART1,','); while(USART_GetFlagStatus(USART1, USART_FLAG_TC) == RESET); USART_SendData(USART1,' '); while(USART_GetFlagStatus(USART1, USART_FLAG_TC) == RESET); adcx=Get_Adc_Average(ADC_Channel_2,10); temp=(float)adcx*(3.3/4096); sprintf(buffer,"%f",temp); for(y=0;y<7;y++) { USART_SendData(USART1,buffer[y]); while(USART_GetFlagStatus(USART1, USART_FLAG_TC) == RESET); } USART_SendData(USART1,','); while(USART_GetFlagStatus(USART1, USART_FLAG_TC) == RESET); USART_SendData(USART1,' '); while(USART_GetFlagStatus(USART1, USART_FLAG_TC) == RESET); adcx=Get_Adc_Average(ADC_Channel_3,10); temp=(float)adcx*(3.3/4096); sprintf(buffer,"%f",temp); for(y=0;y<7;y++) { USART_SendData(USART1,buffer[y]); while(USART_GetFlagStatus(USART1, USART_FLAG_TC) == RESET); } USART_SendData(USART1,','); while(USART_GetFlagStatus(USART1, USART_FLAG_TC) == RESET); USART_SendData(USART1,' '); while(USART_GetFlagStatus(USART1, USART_FLAG_TC) == RESET); adcx=Get_Adc_Average(ADC_Channel_4,10); temp=(float)adcx*(3.3/4096); sprintf(buffer,"%f",temp); for(y=0;y<7;y++) { USART_SendData(USART1,buffer[y]); while(USART_GetFlagStatus(USART1, USART_FLAG_TC) == RESET); } USART_SendData(USART1,','); while(USART_GetFlagStatus(USART1, USART_FLAG_TC) == RESET); USART_SendData(USART1,' '); while(USART_GetFlagStatus(USART1, USART_FLAG_TC) == RESET); adcx=Get_Adc_Average(ADC_Channel_5,10); temp=(float)adcx*(3.3/4096); sprintf(buffer,"%f",temp); for(y=0;y<7;y++) { USART_SendData(USART1,buffer[y]); while(USART_GetFlagStatus(USART1, USART_FLAG_TC) == RESET); } USART_SendData(USART1,','); while(USART_GetFlagStatus(USART1, USART_FLAG_TC) == RESET); USART_SendData(USART1,' '); while(USART_GetFlagStatus(USART1, USART_FLAG_TC) == RESET); adcx=Get_Adc_Average(ADC_Channel_6,10); temp=(float)adcx*(3.3/4096); sprintf(buffer,"%f",temp); for(y=0;y<7;y++) { USART_SendData(USART1,buffer[y]); while(USART_GetFlagStatus(USART1, USART_FLAG_TC) == RESET); } USART_SendData(USART1,','); while(USART_GetFlagStatus(USART1, USART_FLAG_TC) == RESET); USART_SendData(USART1,' '); while(USART_GetFlagStatus(USART1, USART_FLAG_TC) == RESET); adcx=Get_Adc_Average(ADC_Channel_7,10); temp=(float)adcx*(3.3/4096); sprintf(buffer,"%f",temp); for(y=0;y<7;y++) { USART_SendData(USART1,buffer[y]); while(USART_GetFlagStatus(USART1, USART_FLAG_TC) == RESET); } USART_SendData(USART1,','); while(USART_GetFlagStatus(USART1, USART_FLAG_TC) == RESET); USART_SendData(USART1,' '); while(USART_GetFlagStatus(USART1, USART_FLAG_TC) == RESET); adcx=Get_Adc_Average(ADC_Channel_8,10); temp=(float)adcx*(3.3/4096); sprintf(buffer,"%f",temp); for(y=0;y<7;y++) { USART_SendData(USART1,buffer[y]); while(USART_GetFlagStatus(USART1, USART_FLAG_TC) == RESET); } USART_SendData(USART1,','); while(USART_GetFlagStatus(USART1, USART_FLAG_TC) == RESET); USART_SendData(USART1,' '); while(USART_GetFlagStatus(USART1, USART_FLAG_TC) == RESET); } }[/mw_shl_code]