ADC Example

Source code path: example\rt_device\adc\channel

Warning

Not verified

Supported Platforms

The example can run on the following development boards.

sf32lb52-lcd_n16r8
sf32lb52-lcd_52d
sf32lb58-lcd_n16r64n4

Overview

Under RT-Thread operating system, ADC single-channel sampling demonstration

Example Usage

Compilation and Flashing

This example uses ADC. Under RT-Thread operating system, ADC peripheral is virtualized as an rt_device for read/write operations. At this time, you need to confirm whether the rtconfig.h file in the current path contains the following 2 macros:

#define BSP_USING_ADC 1 #define BSP_USING_ADC1 1 #define RT_USING_ADC 1

Only when the above three macros are included, the sifli_adc_init function will register the "bat1" rt_device through the rt_hw_adc_register function, and then the device can be successfully found with rt_device_find and controlled with rt_device_control.
Note
SiFli series MCUs support timer interrupt to trigger multi-channel simultaneous sampling. You can refer to the definition within macro BSP_GPADC_SUPPORT_MULTI_CH_SAMPLING and the chip user manual

If the above three macros are missing, you need to enable them through menuconfig with the following command

menuconfig –board=sf32lb52-lcd_n16r8 525 development board menuconfig –board=sf32lb52-lcd_52d 52d development board menuconfig –board=sf32lb58-lcd_n16r64n4 587 development board

As shown in the figure below, select GPADC1, save and exit menuconfig, check if the rtconfig.h macro is generated alt text

Switch to the example project directory and run the scons command to compile:

scons –board=em-‘bread nmae’ -j8

Switch to the example project/build_xx directory and run uart_download.bat, select the port as prompted to download:

build_sf32lb52-lcd_n16r8_hcpu\uart_download.bat

Uart Download

please input the serial port num:5

sf32lb58-lcd_n16r64n4 Flashing

sf32lb58-lcd_n16r64n4 flashing is different from 52 series flashing and requires J-link for flashing. Connect J-link with development board and PC alt text In J-Link Commander, input ‘connect’ and ‘?’ commands to select the corresponding model to complete connection. Successful connection is shown below:

alt text After successful connection, return to ConEmu and input ‘build_sf32lb58-lcd_n16r64n4_hcpu\download.bat’ for flashing

Hardware Connection (52 Series)

PA28 is the fixed output IO for ADC1 Channel 0

Hardware Connection (587)

PB34 is the fixed output IO for ADC1 Channel 2

Example Output Results Display:

Log output:

   SFBL
   Serial:c2,Chip:4,Package:3,Rev:3  Reason:00000080
    \ | /
   - SiFli Corporation
    / | \     build on Nov  5 2024, 2.2.0 build 00000000
    2020 - 2022 Copyright by SiFli team
   mount /dev sucess
   [32m][490] I/drv.rtc: PSCLR=0x80000100 DivAI=128 DivAF=0 B=256
   [0m][32m][516] I/drv.rtc: RTC use LXT RTC_CR=00000001
   [0m][32m][538] I/drv.rtc: Init RTC, wake = 1
   [0m][32m][565] I/drv.audprc: init 00 ADC_PATH_CFG0 0x606
   [0m][32m][587] I/drv.audprc: HAL_AUDPRC_Init res 0
   [0m][32m][608] I/drv.audcodec: HAL_AUDCODEC_Init res 0
   [0m][32m][630] I/TOUCH: Regist touch screen driver, probe=1203bf69 
   [0mcall par CFG1](35bb)
   fc 9, xtal 2000, pll 2051
   call par CFG1(35bb)
   fc 9, xtal 2000, pll 2051
   Start adc demo!
   adc control origin data 2783, Voltage 20846
   [32m][828] I/adc: adc channel:0,value:20846
   [0m]msh />[32m][1567] I/adc: rt_adc_read:0,value:20700
   [0m]spi adc end!

The log printed value is in 0.1mV units, 20846 equals 2084.6mV or 2.0846V

ADC Configuration Process

Ensure the rtconfig.h file contains the following 4 macros:

#define BSP_USING_ADC 1 #define BSP_USING_ADC1 1 #define RT_USING_ADC 1

Configure PA28 port corresponding to ADC1 Channel 0

    \* set pinmux of channel 0 to analog input *\
    HAL_PIN_Set_Analog(PAD_PA28, 1);

Note

ADC input ports are fixed IO ports, as shown in the figure below:
52 chip ADC CH1-7 distribution, corresponding to software configured Channel0-6, the last channel CH8(Channel 7) is internally connected to battery Vbat detection and is not mapped to external IO
HAL_PIN_Set HAL_PIN_Set_Analog the last parameter is for hcpu/lcpu selection, 1: select hcpu, 0: select lcpu

Use rt_device_find and rt_device_control sequentially to find and configure the bat1 device interface function. rt_adc_ops does not define rt_device_open, so not executing rt_device_open will not affect ADC functionality, it will only affect whether bat1 shows open status in list_device

#define ADC_DEV_NAME        "bat1"      /* ADC1 device, already registered in rt_hw_adc_register function, cannot be modified arbitrarily */
#define ADC_DEV_CHANNEL     0           /* ADC channel selection PA28 fixed to CH1(Channel 0) */
//#define REFER_VOLTAGE       330         /* ADC reference voltage, 52 chip can choose 1v8 or 3v3, interface is not currently open, fixed to 3V3 */
static rt_device_t s_adc_dev; /* Define an rt_device device */
static rt_adc_cmd_read_arg_t read_arg;

void adc_example(void)
{
    rt_err_t r;

    /* Configure PA28 as analog input IO and cannot enable internal pull-up/pull-down */
    HAL_PIN_Set_Analog(PAD_PA28, 1);

    /* Find bat1 device, if BSP_USING_ADC1 is not enabled, device will not be found and system will hang */
    s_adc_dev = rt_device_find(ADC_DEV_NAME);

    /* Configure sampling channel to channel 0*/
    read_arg.channel = ADC_DEV_CHANNEL;

    r = rt_adc_enable((rt_adc_device_t)s_adc_dev, read_arg.channel);
    
    /* This interface will call sifli_adc_control function, read only once, users can process data themselves */   
    r = rt_device_control(s_adc_dev, RT_ADC_CMD_READ, &read_arg.channel);
    /* Log printed value is in 0.1mV units, 20846 equals 2084.6mV or 2.0846V  */
    LOG_I("adc channel:%d,value:%d",read_arg.channel,read_arg.value); /* (0.1mV), 20846 is 2084.6mV or 2.0846V */

    /* This demonstrates another way to perform ADC sampling, this interface will call sifli_get_adc_value function, will perform default 22 times averaging  */
    rt_uint32_t value = rt_adc_read((rt_adc_device_t)s_adc_dev, ADC_DEV_CHANNEL);
    /* Log printed value is in 0.1mV units, 20700 equals 2070.0mV or 2.0700V  */
    LOG_I("rt_adc_read:%d,value:%d",read_arg.channel,value); /* (0.1mV), 20700 is 2070mV or 2.070V */

    /* After sampling is complete, close adc */
    rt_adc_disable((rt_adc_device_t)s_adc_dev, read_arg.channel);

}

Exception Diagnosis

Program crashes with the following log

   Start adc demo!
   Assertion failed at function:rt_adc_enable, line number:144 ,(dev)
   Previous ISR enable 0

Reason:
BSP_USING_ADC1 is not defined, causing rt_hw_adc_register function to not register "bat1", and Assert crashes when rt_device_find searches for this device
Ensure the rtconfig.h file contains the following 3 macros:

#define BSP_USING_ADC 1
#define BSP_USING_ADC1 1
#define RT_USING_ADC 1

ADC sampled voltage value is incorrect

Use pin status 28 command to check the corresponding PA28 IO status, whether it matches the following

     msh />
 TX:pin status 28
    pin status 28
    [32m][372862432] I/TEST.GPIO: PIN 28, FUNC=15, VAL=0, ANA_IN, GPIO_MODE_INPUT, irqhdr=/, arg=/
    [0m]msh />

Use list_device command to check if bat1 device exists. ADC driver does not affect ADC functionality when bat1 device is not opened with rt_device_open

    msh />
 TX:list_device
    list_device
    device           type         ref count
    -------- -------------------- ----------
    audcodec Sound Device         0       
    audprc   Sound Device         0       
    rtc      RTC                  0       
    pwm3     Miscellaneous Device 0       
    pwm2     Miscellaneous Device 0       
    touch    Graphic Device       0       
    lcdlight Character Device     0       
    lcd      Graphic Device       0       
    bat1     Miscellaneous Device 0       
    i2c4     I2C Bus              0       
    i2c1     I2C Bus              0       
    spi1     SPI Bus              0       
    lptim1   Timer Device         0       
    btim1    Timer Device         0       
    gptim1   Timer Device         0       
    uart2    Character Device     0       
    uart1    Character Device     2       
    pin      Miscellaneous Device 0       
    msh />

Check if ADC hardware is connected correctly. ADC sampling channels are fixed IO ports and cannot be specified arbitrarily. For specific CH0-7 IO assignments, refer to the chip manual
ADC input voltage range is 0V - reference voltage (52 defaults to 3v3), cannot exceed input range

ADC accuracy is insufficient

Whether ADC calibration parameters are obtained and used
Whether the accuracy of voltage divider resistors meets requirements
Whether ADC reference voltage is stable and has excessive ripple (refer to ADC voltage reference chip manual for details)

Reference Documents

EH-SF32LB52X_Pin_config_V1.3.0_20231110.xlsx
DS0052-SF32LB52x-芯片技术规格书 V0p3.pdf
RT-Thread Official Website
https://www.rt-thread.org/document/site/#/rt-thread-version/rt-thread-standard/programming-manual/device/adc/adc

Update History

Version	Date	Release Notes
0.0.1	11/2024	Initial version