[参考译文] ADS8691：ADS8691 SPI 通信问题

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https://e2e.ti.com/support/data-converters-group/data-converters/f/data-converters-forum/1275753/ads8691-ads8691-spi-communication-issue

器件型号：ADS8691

您好！

我对您的 ADC 有一些问题：ADS8691IPW。

主要问题是缺乏可靠的工作。

它通过跳线连接到 STM32F411E-DISCOS 开发板。

ADC 本身焊接在执行板上以用于调试。
它主要内置于具有四个菊花链单元的定制 PCB 中、但问题是类似的。

STM 由 USB 供电、ADC 模拟端和数字端通过 Keithley SMU 提供5V 电压。
使用1uF 电解电容器进行去耦。

我已经通过具有类似效果的多个 ADC 进行了迭代。

问题是它仅在连接示波器时起作用。
但在重新设置 STM 或将接地端连接到逻辑分析仪或将数字引脚连接到逻辑分析仪后、或一段时间后、它会停止工作。

我可以通过以下方式使其正常工作：

为 ADC 重置跳线、

断开跳线与逻辑分析仪的连接、

断开逻辑分析仪的接地、

重新连接到逻辑分析仪、

和许多其他组合。

定制 PCB ADC 原理图：

在定制 PCB 上、由于寄生引起的过冲和下冲显著降低。
绕过是根据指南进行的。

请注意、还有一个接地引线电感、它看起来会更糟。

(在所有屏幕中、示波器在 SPI 总线上触发)
当它工作时、数据会清晰地显示

有时在重置后、看起来是这样的：

或者根本无法正常工作。

我还在 MCU 以及靠近 ADC 的硬件中尝试了上拉和下拉电阻。

此外、还测试了不同的 CLK 速度。

代码：

来自 main 的零件：

void HAL_GPIO_EXTI_Callback(uint16_t GPIO_Pin)
{
	if(GPIO_Pin == ADC_ALARM_Pin)
	{
	   //This block will be triggered after pin activated.
		if(BUTTON_Pin == 1)
		{
			for(int i = 0; i < 4; i++)
			{
			read_hword_data();
	    	char *msg = "ADC Alarm working\r\n";
	        HAL_UART_Transmit(&huart2, msg, sizeof(msg), 100);
			}
		}
	}
}

void HAL_SPI_RxCpltCallback(SPI_HandleTypeDef * hspi)
{
    HAL_SPI_Receive_DMA(&hspi1, RX_Buffer, sizeof(RX_Buffer));
    if(sample < 50000)
    {
    	read_adc_data(&adc_handle, RX_Buffer, sample);
    	sample++;
    }
    else if(sample == 50000)
    {
    	char *msg = "50 000 samples gathered\r\n";
        HAL_UART_Transmit(&huart2, msg, sizeof(msg), 100);
    }

}

自定义库：

struct adc_state adc_init() {
	struct adc_state state;
/*
	for(uint16_t i=0; i<12500; i++) state.data0[i] = '\0';
	for(uint16_t i=0; i<12500; i++) state.data1[i] = '\0';
	for(uint16_t i=0; i<12500; i++) state.data2[i] = '\0';
	for(uint16_t i=0; i<12500; i++) state.data3[i] = '\0';
*/
	return state;
}

/*
 * 11000_xx_<9-bit address>_ <16-bit data>
 * Command used to clear any (or a group of) bits of a register.
 * Any bit marked 1 in the data field results in that particular bit of the specified register being reset to 0, leaving the other bits unchanged.
 * Half-word command (that is, the command functions on 16 bits at a time).
 * LSB of the 9-bit address is always ignored and considered as 0b.(2)
 */
void clear_hword(char *reg)
{
	char command[16];
	sprintf(command, "11000000%s", reg);
	HAL_SPI_Transmit(&hspi1, command, sizeof(command), 0);
}

/*
 * 11001_xx_<9-bit address>_ 00000000_00000000
 * Command used to perform a 16-bit read operation.
 * Half-word command (that is, the device outputs 16 bits of register data at a time).
 * LSB of the 9-bit address is always ignored and considered as 0b.
 * Upon receiving this command, the device sends out 16 bits of the register in the next frame.
 */
void read_hword(char *reg)
{
	char x[8] = "00000000";
	char command[16];
	sprintf(command, "11001000%s", reg);
	HAL_SPI_Transmit(&hspi1, command, sizeof(command), 0);
	HAL_SPI_Transmit(&hspi1, x, sizeof(x), 0);
}


void read_hword_data()
{
	if(HAL_GPIO_ReadPin(GPIOA, GPIO_PIN_3) == 1)
		{
			HAL_GPIO_WritePin(GPIOA, GPIO_PIN_4, GPIO_PIN_RESET);
			for(int i = 0; i < 4; i++)
			{
				read_hword(DATAOUT_CTL_REG);
			}
			HAL_GPIO_WritePin(GPIOA, GPIO_PIN_4, GPIO_PIN_SET);
		}
}

/*
 * 01001_xx_<9-bit address>_ 00000000_00000000
 * Same as the READ_HWORD except that only eight bits of the register (byte read) are returned in the next frame.
*/
void read_word(char *reg)
{
	char command[16];
	sprintf(command, "01001000%s", reg);
	HAL_SPI_Transmit(&hspi1, command, sizeof(command), 0);
}

/*
 * 11010_00_<9-bit address>_ <16-bit data>
 * Half-word write command (two bytes of input data are written into the specified address).
 * LSB of the 9-bit address is always ignored and considered as 0b.
 *
 * 11010_01_<9-bit address>_ <16-bit data>
 * Half-word write command.
 * LSB of the 9-bit address is always ignored and considered as 0b.
 * With this command, only the MS byte of the 16-bit data word is written at the specified register address. The LS byte is ignored.
 *
 * 11010_10_<9-bit address>_ <16-bit data>
 * Half-word write command.
 * LSB of the 9-bit address is always ignored and considered as 0b.
 * With this command, only the LS byte of the 16-bit data word is written at the specified register address. The MS byte is ignored.
 */
void write_word(char *reg)
{
	char command[16];
	sprintf(command, "11010000%s", reg);
	HAL_SPI_Transmit(&hspi1, command, sizeof(command), 0);
}

/*
 * 11011_xx_<9-bit address>_ <16-bit data>
 * Command used to set any (or a group of) bits of a register.
 * Any bit marked 1 in the data field results in that particular bit of the specified register being set to 1, leaving the other bits unchanged.
 * Half-word command (that is, the command functions on 16 bits at a time).
 * LSB of the 9-bit address is always ignored and considered as 0b.
 */
void set_hword(char *reg)
{
	char command[16];
	sprintf(command, "11011000%s", reg);
	HAL_SPI_Transmit(&hspi1, command, sizeof(command), 0);
}

/*
 * Configuration described in the documentation in chapter "7.6 Register Maps" (p.48)
 * www.ti.com/.../ads8691.pdf
 */
void id_config()
{
	if(HAL_GPIO_ReadPin(GPIOA, GPIO_PIN_3) == 1)
	{
		HAL_GPIO_WritePin(GPIOA, GPIO_PIN_4, GPIO_PIN_RESET);
		for(int i = 0; i < 4; i++)
		{
			write_word(DEVICE_ID_REG);
			char command[16];
			sprintf(command,"0000000000000000");
			HAL_SPI_Transmit(&hspi1, command, sizeof(command), 10);
		}
		HAL_GPIO_WritePin(GPIOA, GPIO_PIN_4, GPIO_PIN_SET);
	}
}

/*
 * Configuration described in the documentation in chapter "7.6 Register Maps" (p.48)
 * www.ti.com/.../ads8691.pdf
 */
void reset_config()
{
	if(HAL_GPIO_ReadPin(GPIOA, GPIO_PIN_3) == 1)
	{
		HAL_GPIO_WritePin(GPIOA, GPIO_PIN_4, GPIO_PIN_RESET);
		for(int i = 0; i < 4; i++)
		{
			write_word(RST_PWRCTL_REG);
			char command[16];
			sprintf(command,"0100010100100000");
			HAL_SPI_Transmit(&hspi1, command, sizeof(command), 10);
		}
		HAL_GPIO_WritePin(GPIOA, GPIO_PIN_4, GPIO_PIN_SET);
	}
}

/*
 * Configuration described in the documentation in chapter "7.6 Register Maps" (p.48)
 * www.ti.com/.../ads8691.pdf
 */
void sdi_config()
{
	if(HAL_GPIO_ReadPin(GPIOA, GPIO_PIN_3) == 1)
	{
		HAL_GPIO_WritePin(GPIOA, GPIO_PIN_4, GPIO_PIN_RESET);
		for(int i = 0; i < 4; i++)
		{
			write_word(SDI_CTL_REG);
			char command[16];
			sprintf(command,"0000000000000000");
			HAL_SPI_Transmit(&hspi1, command, sizeof(command), 10);
		}
		HAL_GPIO_WritePin(GPIOA, GPIO_PIN_4, GPIO_PIN_SET);
	}
}

/*
 * Configuration described in the documentation in chapter "7.6 Register Maps" (p.48)
 * www.ti.com/.../ads8691.pdf
 */
void sdo_config()
{
	if(HAL_GPIO_ReadPin(GPIOA, GPIO_PIN_3) == 1)
	{
		HAL_GPIO_WritePin(GPIOA, GPIO_PIN_4, GPIO_PIN_RESET);
		for(int i = 0; i < 4; i++)
		{
			write_word(SDO_CTL_REG);
			char command[16];
			sprintf(command,"0000000100000000");
			HAL_SPI_Transmit(&hspi1, command, sizeof(command), 10);
		}
		HAL_GPIO_WritePin(GPIOA, GPIO_PIN_4, GPIO_PIN_SET);
	}
}

/*
 * Configuration described in the documentation in chapter "7.6 Register Maps" (p.48)
 * www.ti.com/.../ads8691.pdf
 */
void data_config()
{
	if(HAL_GPIO_ReadPin(GPIOA, GPIO_PIN_3) == 1)
	{
		HAL_GPIO_WritePin(GPIOA, GPIO_PIN_4, GPIO_PIN_RESET);
		for(int i = 0; i < 4; i++)
		{
			write_word(DATAOUT_CTL_REG);
			char command[16];
			sprintf(command,"0100110000000000");
			HAL_SPI_Transmit(&hspi1, command, sizeof(command), 10);
		}
		HAL_GPIO_WritePin(GPIOA, GPIO_PIN_4, GPIO_PIN_SET);
	}
}

/*
 * Configuration described in the documentation in chapter "7.6 Register Maps" (p.48)
 * www.ti.com/.../ads8691.pdf
 */
void ref_vol_config()
{
	if(HAL_GPIO_ReadPin(GPIOA, GPIO_PIN_3) == 1)
	{
		HAL_GPIO_WritePin(GPIOA, GPIO_PIN_4, GPIO_PIN_RESET);
		for(int i = 0; i < 4; i++)
		{
			write_word(RANGE_SEL_REG);
			char command[16];
			sprintf(command,"0000000000000000");
			HAL_SPI_Transmit(&hspi1, command, sizeof(command), 10);
		}
		HAL_GPIO_WritePin(GPIOA, GPIO_PIN_4, GPIO_PIN_SET);
	}
}

/*
 * Configuration described in the documentation in chapter "7.6 Register Maps" (p.48)
 * www.ti.com/.../ads8691.pdf
 */
void alarms_config()
{
	if(HAL_GPIO_ReadPin(GPIOA, GPIO_PIN_3) == 1)
	{
		HAL_GPIO_WritePin(GPIOA, GPIO_PIN_4, GPIO_PIN_RESET);
		for(int i = 0; i < 4; i++)
		{
			write_word(ALARM_REG);
			char command[16];
			sprintf(command,"0000110000000000");
			HAL_SPI_Transmit(&hspi1, command, sizeof(command), 10);
		}
		HAL_GPIO_WritePin(GPIOA, GPIO_PIN_4, GPIO_PIN_SET);
	}
}

/*
 * Configuration described in the documentation in chapter "7.6 Register Maps" (p.48)
 * www.ti.com/.../ads8691.pdf
 */
void alarmh_config()
{
	if(HAL_GPIO_ReadPin(GPIOA, GPIO_PIN_3) == 1)
	{
		HAL_GPIO_WritePin(GPIOA, GPIO_PIN_4, GPIO_PIN_RESET);
		for(int i = 0; i < 4; i++)
		{
			write_word(ALARM_H_TH_REG);
			char command[16];
			sprintf(command,"0000000000000000");
			HAL_SPI_Transmit(&hspi1, command, sizeof(command), 10);
		}
		HAL_GPIO_WritePin(GPIOA, GPIO_PIN_4, GPIO_PIN_SET);
	}
}

/*
 * Configuration described in the documentation in chapter "7.6 Register Maps" (p.48)
 * www.ti.com/.../ads8691.pdf
 */
void alarml_config()
{
	if(HAL_GPIO_ReadPin(GPIOA, GPIO_PIN_3) == 1)
	{
		HAL_GPIO_WritePin(GPIOA, GPIO_PIN_4, GPIO_PIN_RESET);
		for(int i = 0; i < 4; i++)
		{
			write_word(ALARM_L_TH_REG);
			char command[16];
			sprintf(command,"0000000000000000");
			HAL_SPI_Transmit(&hspi1, command, sizeof(command), 10);		}
		HAL_GPIO_WritePin(GPIOA, GPIO_PIN_4, GPIO_PIN_SET);
	}
}

// Initialization of all ADC's registers
void adc_config()
{
	id_config();
	reset_config();
	sdi_config();
	sdo_config();
	data_config();
	ref_vol_config();
	alarms_config();
	alarmh_config();
	alarml_config();

}

//
void read_adc_data(struct adc_state *state, uint8_t *val, uint16_t x)
{
	x = x/4;
	receiver_check(state, val, x);
	read_hword_data();

}

//
void receiver_check(struct adc_state *state, uint8_t *val, uint16_t x)
{
	int16_t data;
	data = (val[3] << 8) | val[2];

2 年多前

0 admin 2 年多前

TI__Guru**** 2482225 points

请注意，本文内容源自机器翻译，可能存在语法或其它翻译错误，仅供参考。如需获取准确内容，请参阅链接中的英语原文或自行翻译。

大家好、Radoslaw、

感谢您的发帖。

我将通过尝试一些方法来开始调试、以提高设置的稳健性。几个指针：

在 ADC 板、STM 板和外部电源之间共享一个实心 GND 连接。还要确保 AIN_GND 和 DGND 之间的接地连接牢固。通常建议使用共用接地。
为了减少 SPI 线路上的过冲和振铃、添加一些串联端接(即33欧姆)来抑制高频成分。 SCLK 上的小电容(即10 pF)也有助于实现相同目的。这可能就是示波器探头看似有用的原因。
一旦电源接通并稳定、复位脉冲可能有助于确保所有 ADC 在已知正常状态下加电。然后、如有必要、继续配置所有寄存器。

此致、

瑞安

0 admin 2 年多前

TI__Guru**** 2482225 points

请注意，本文内容源自机器翻译，可能存在语法或其它翻译错误，仅供参考。如需获取准确内容，请参阅链接中的英语原文或自行翻译。

您好、Ryan、

非常感谢您的答复、很遗憾、我的问题没有得到解决。

我已应用所有建议的更改以及增加电容以增加 HF 负载。
出于某种原因、我可以通过用手指触摸引脚使其工作、但仅当"Reset"悬空且在建立数据传输后、将其拉高。

它看起来像是存在信号完整性问题、但根据数据表执行的所有操作都无法正常工作。

测量所有引脚和电源电压后、也不存在禁止状态。

可能我拥有的单元有缺陷。

0 admin 2 年多前

TI__Guru**** 2482225 points

请注意，本文内容源自机器翻译，可能存在语法或其它翻译错误，仅供参考。如需获取准确内容，请参阅链接中的英语原文或自行翻译。

您好 Radosaw、

RSTN 引脚不应悬空。它应该始终被驱动为高电平或低电平。默认情况下、RSTN 引脚用于上电复位(POR)。在 POR 延时时间(TD_RST_POR)之后、您可以将 RSTn 拉高并开始数据采集。

到目前为止、这似乎不是器件问题。如您所说、它有时会起作用。我相信、改进设置和上电序列将产生更一致的结果。

此致、

瑞安

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[参考译文] ADS8691：ADS8691 SPI 通信问题