[参考译文] DAC7750：即使是、也不会在 IC 的 Iout 引脚上传入电流

https://e2e.ti.com/support/data-converters-group/data-converters/f/data-converters-forum/998372/dac7750-current-not-comming-at-iout-pin-of-ic-even-though

PCB 上的连接图像： PCV_DAC7750

我已最小化与 DAC7750的连接、即 AVDD (=11.5V)、SDO、DIN、SCK、LATCH、 如 PCB 中所示的 GND (链接至上图)。  我只是使用 ESP32内置 SPI 库进行电流斜升和斜降。 我还面临同样的问题、因为未在输出端检测到电流(使用电流表进行测量)。 AVDD 在10V 至18V 范围内变化、但仍然存在相同的问题。 DVDD 未连接、因为 DVDD_EN 处于开路状态、这意味着为内部数字外设启用内部电源。 我已经通过示波器验证了在 ESP32引脚上生成的 MOSI、SCL、SS 信号。 我使用了控制器的 HSPI 端口。 我一直保持较高的延迟、以便在示波器上轻松调试。  

#include <SPI.h>

//#define ALARM  
#define HSPI_MISO   12
#define HSPI_MOSI   13
#define HSPI_SCLK   14
#define HSPI_SS     15    //To be connected to LATCH pin of DAC7750

//see pg32 datasheet
#define Config   0x57
#define Ctrl     0x55
#define DAC_data 0x01
#define Reset    0x56

static const int spiClk = 1000; //freq in Hz

SPIClass SPI2(HSPI);

//Send values to DAC7750 in format 'address_of_register + data' 
//24-bit frame= 8bit addr + 16bit data
//See pg10, Datasheet for timing diagram
void Send(uint8_t addr, uint16_t value)
{ 
  SPI2.transfer(addr);
  SPI2.transfer16(value);    ///inbuilt function in SPI.h for 2bytes transfer
  digitalWrite(HSPI_SS, LOW);
  delay(1);
  digitalWrite(HSPI_SS, HIGH);
  delay(1);
}

void setup()
{ delay(1000);  //Let the power supply be stable. 

  pinMode(HSPI_SS, OUTPUT);
  digitalWrite(HSPI_SS, HIGH); 

//  pinMode(ALARM, INPUT);

  SPI2.begin(HSPI_SCLK, HSPI_MISO, HSPI_MOSI, HSPI_SS);

  SPI2.beginTransaction(SPISettings(spiClk, MSBFIRST, SPI_MODE0));
   
  //INITIALISE REGISTERS (pg34 onwards, Datasheet)
  //..Reset register
  Send(Reset, 0x0001); 
  delay(1);
  
  //..config register 
  Send(Config,0b0000000000001100);   //disable HART, watchdog, error-check, calliberation
  delay(1);
  
  //..Data register   -> initialise with all 0. (But is already at default reset)
  //Send(DAC_data, 0x0000);  //last 4 LSB digits invalid for DAC7750 (to act as 12-bit)
  //delay(1);
  
  //..Control register
  Send(Ctrl, 0b0011000000001110);  //o/p enable, o/p->0-20mA, current setting res enable
  delay(1);
}

void loop() 
{
  //send a ramp from 0 - 2mA, then const upto 30sec, then ramp to 0mA
  //ramp slope around 30sec
  uint16_t i=0;
  for(i=0; i<409; i++)  //Current upto 2mA i.e. 409.5 value of 12bit-DAC in 30sec
  {
    Send(DAC_data, (i<<4));
    delay(75);
  }

  delay(10000);

  for(i=409; i>=0; i--) //Current upto 2mA i.e. 409.5 value of 12bit-DAC in 30sec (16bit register, last 4bits useless)
  {
    Send(DAC_data, (i<<4));
    delay(75);
  }

  delay(10000);
  
}