TMS320F28P550SG: 28P55ADC使用外部2.5V参考电压基准采样值不对

电路板 VREFHI链接外部参考电源芯片的2.5V，VREFLO接模拟地，AD引脚输入1.25V时ADC的转换结果大概只有1180，请帮忙看看ADC初始化哪里出了问题？谢谢

ADC的初始化程序如下：

AdcBaseAddr[0] = ADCA_BASE;
AdcBaseAddr[1] = ADCB_BASE;
AdcBaseAddr[2] = ADCC_BASE;
AdcBaseAddr[3] = ADCD_BASE;
AdcBaseAddr[4] = ADCE_BASE;
SysCtl_enablePeripheral(SYSCTL_PERIPH_CLK_ADCA);
SysCtl_enablePeripheral(SYSCTL_PERIPH_CLK_ADCB);
SysCtl_enablePeripheral(SYSCTL_PERIPH_CLK_ADCC);
SysCtl_enablePeripheral(SYSCTL_PERIPH_CLK_ADCD);
SysCtl_enablePeripheral(SYSCTL_PERIPH_CLK_ADCE);

EALLOW;
ASysCtl_disableTemperatureSensor();
// Set the analog voltage reference selection to external.
ASysCtl_setAnalogReferenceExternal(ASYSCTL_ANAREF_VREFHI_ADCA | ASYSCTL_ANAREF_VREFHI_ADCB | ASYSCTL_ANAREF_VREFHI_ADCC | ASYSCTL_ANAREF_VREFHI_ADCD | ASYSCTL_ANAREF_VREFHI_ADCE);
ASysCtl_setVrefHiReferenceVREFHI(ASYSCTL_ANAREF_VREFHI_ADCA | ASYSCTL_ANAREF_VREFHI_ADCB | ASYSCTL_ANAREF_VREFHI_ADCC | ASYSCTL_ANAREF_VREFHI_ADCD | ASYSCTL_ANAREF_VREFHI_ADCE);
ASysCtl_setVrefLoReferenceVREFLO(ASYSCTL_ANAREF_INTREF_ADCA | ASYSCTL_ANAREF_INTREF_ADCB | ASYSCTL_ANAREF_INTREF_ADCC | ASYSCTL_ANAREF_INTREF_ADCD | ASYSCTL_ANAREF_INTREF_ADCE);
//ASysCtl_setAnalogReference2P5( ASYSCTL_ANAREF_ADCA | ASYSCTL_ANAREF_ADCB | ASYSCTL_ANAREF_ADCC | ASYSCTL_ANAREF_ADCD | ASYSCTL_ANAREF_ADCE );// Set the internal analog voltage reference selection to 2.5V.
// ADC Initialization: Write ADC configurations and power up the ADC
for(i = 0; i < 5; i++)
{
ADC_setVREF(AdcBaseAddr[i], ADC_REFERENCE_EXTERNAL, ADC_REFERENCE_VREFHI);
//ADC_setOffsetTrim(AdcBaseAddr[i]);
ADC_setPrescaler(AdcBaseAddr[i], ADC_CLK_DIV_2_0);// Configures the analog-to-digital converter module prescaler.
ADC_setInterruptPulseMode(AdcBaseAddr[i], ADC_PULSE_END_OF_CONV);// Sets the timing of the end-of-conversion pulse
ADC_enableConverter(AdcBaseAddr[i]);// Powers up the analog-to-digital converter core.
DEVICE_DELAY_US(5000);// Delay for 1ms to allow ADC time to power up
//ADC_enableAltDMATiming(AdcBaseAddr[i]);// Enable alternate timings for DMA trigger
ADC_disableBurstMode(AdcBaseAddr[i]);// Disables SOC burst mode.
ADC_setSOCPriority(AdcBaseAddr[i], ADC_PRI_ALL_HIPRI);// Sets the priority mode of the SOCs.
}
DEVICE_DELAY_US(50000);

Links：

您好，

已经收到了您的案例，调查需要些时间，感谢您的耐心等待。

TRANSLATE with x

English

Arabic
Hebrew
Polish

Bulgarian
Hindi
Portuguese

Catalan
Hmong Daw
Romanian

Chinese Simplified
Hungarian
Russian

Chinese Traditional
Indonesian
Slovak

Czech
Italian
Slovenian

Danish
Japanese
Spanish

Dutch
Klingon
Swedish

English
Korean
Thai

Estonian
Latvian
Turkish

Finnish
Lithuanian
Ukrainian

French
Malay
Urdu

German
Maltese
Vietnamese

Greek
Norwegian
Welsh

Haitian Creole
Persian

TRANSLATE with

COPY THE URL BELOW

Back

EMBED THE SNIPPET BELOW IN YOUR SITE

Enable collaborative features and customize widget: Bing Webmaster Portal
Back