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esp32驱动max30102芯片初始化篇二_max30102 esp32

max30102 esp32

MAX3010X初始化部分

byte ledBrightness = 60; //Options: 0=Off to 255=50mA
byte sampleAverage = 4; //Options: 1, 2, 4, 8, 16, 32
byte ledMode = 2; //Options: 1 = Red only, 2 = Red + IR, 3 = Red + IR + Green
byte sampleRate = 100; //Options: 50, 100, 200, 400, 800, 1000, 1600, 3200
int pulseWidth = 411; //Options: 69, 118, 215, 411
int adcRange = 4096; //Options: 2048, 4096, 8192, 16384

particleSensor.setup(ledBrightness, sampleAverage, ledMode, sampleRate, pulseWidth, adcRange); //Configure sensor with these settings
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这里开始设置MAX3010X的各种参数,对其进行初始化。直接看函数原型吧

MAX30105::setup

在H文件中的定义如下

void setup(byte powerLevel = 0x1F, byte sampleAverage = 4, byte ledMode = 3, int sampleRate = 400, int pulseWidth = 411, int adcRange = 4096);
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也都是可选参数

CPP文件中的实现如下

void MAX30105::setup(byte powerLevel, byte sampleAverage, byte ledMode, int sampleRate, int pulseWidth, int adcRange) {
  softReset(); //Reset all configuration, threshold, and data registers to POR values

  //FIFO Configuration
  //-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
  //The chip will average multiple samples of same type together if you wish
  if (sampleAverage == 1) setFIFOAverage(MAX30105_SAMPLEAVG_1); //No averaging per FIFO record
  else if (sampleAverage == 2) setFIFOAverage(MAX30105_SAMPLEAVG_2);
  else if (sampleAverage == 4) setFIFOAverage(MAX30105_SAMPLEAVG_4);
  else if (sampleAverage == 8) setFIFOAverage(MAX30105_SAMPLEAVG_8);
  else if (sampleAverage == 16) setFIFOAverage(MAX30105_SAMPLEAVG_16);
  else if (sampleAverage == 32) setFIFOAverage(MAX30105_SAMPLEAVG_32);
  else setFIFOAverage(MAX30105_SAMPLEAVG_4);

  //setFIFOAlmostFull(2); //Set to 30 samples to trigger an 'Almost Full' interrupt
  enableFIFORollover(); //Allow FIFO to wrap/roll over
  //-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

  //Mode Configuration
  //-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
  if (ledMode == 3) setLEDMode(MAX30105_MODE_MULTILED); //Watch all three LED channels
  else if (ledMode == 2) setLEDMode(MAX30105_MODE_REDIRONLY); //Red and IR
  else setLEDMode(MAX30105_MODE_REDONLY); //Red only
  activeLEDs = ledMode; //Used to control how many bytes to read from FIFO buffer
  //-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

  //Particle Sensing Configuration
  //-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
  if(adcRange < 4096) setADCRange(MAX30105_ADCRANGE_2048); //7.81pA per LSB
  else if(adcRange < 8192) setADCRange(MAX30105_ADCRANGE_4096); //15.63pA per LSB
  else if(adcRange < 16384) setADCRange(MAX30105_ADCRANGE_8192); //31.25pA per LSB
  else if(adcRange == 16384) setADCRange(MAX30105_ADCRANGE_16384); //62.5pA per LSB
  else setADCRange(MAX30105_ADCRANGE_2048);

  if (sampleRate < 100) setSampleRate(MAX30105_SAMPLERATE_50); //Take 50 samples per second
  else if (sampleRate < 200) setSampleRate(MAX30105_SAMPLERATE_100);
  else if (sampleRate < 400) setSampleRate(MAX30105_SAMPLERATE_200);
  else if (sampleRate < 800) setSampleRate(MAX30105_SAMPLERATE_400);
  else if (sampleRate < 1000) setSampleRate(MAX30105_SAMPLERATE_800);
  else if (sampleRate < 1600) setSampleRate(MAX30105_SAMPLERATE_1000);
  else if (sampleRate < 3200) setSampleRate(MAX30105_SAMPLERATE_1600);
  else if (sampleRate == 3200) setSampleRate(MAX30105_SAMPLERATE_3200);
  else setSampleRate(MAX30105_SAMPLERATE_50);

  //The longer the pulse width the longer range of detection you'll have
  //At 69us and 0.4mA it's about 2 inches
  //At 411us and 0.4mA it's about 6 inches
  if (pulseWidth < 118) setPulseWidth(MAX30105_PULSEWIDTH_69); //Page 26, Gets us 15 bit resolution
  else if (pulseWidth < 215) setPulseWidth(MAX30105_PULSEWIDTH_118); //16 bit resolution
  else if (pulseWidth < 411) setPulseWidth(MAX30105_PULSEWIDTH_215); //17 bit resolution
  else if (pulseWidth == 411) setPulseWidth(MAX30105_PULSEWIDTH_411); //18 bit resolution
  else setPulseWidth(MAX30105_PULSEWIDTH_69);
  //-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

  //LED Pulse Amplitude Configuration
  //-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
  //Default is 0x1F which gets us 6.4mA
  //powerLevel = 0x02, 0.4mA - Presence detection of ~4 inch
  //powerLevel = 0x1F, 6.4mA - Presence detection of ~8 inch
  //powerLevel = 0x7F, 25.4mA - Presence detection of ~8 inch
  //powerLevel = 0xFF, 50.0mA - Presence detection of ~12 inch

  setPulseAmplitudeRed(powerLevel);
  setPulseAmplitudeIR(powerLevel);
  setPulseAmplitudeGreen(powerLevel);
  setPulseAmplitudeProximity(powerLevel);
  //-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

  //Multi-LED Mode Configuration, Enable the reading of the three LEDs
  //-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
  enableSlot(1, SLOT_RED_LED);
  if (ledMode > 1) enableSlot(2, SLOT_IR_LED);
  if (ledMode > 2) enableSlot(3, SLOT_GREEN_LED);
  //enableSlot(1, SLOT_RED_PILOT);
  //enableSlot(2, SLOT_IR_PILOT);
  //enableSlot(3, SLOT_GREEN_PILOT);
  //-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

  clearFIFO(); //Reset the FIFO before we begin checking the sensor
}
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看起来挺长的,但是都是类似与枚举的if-else,不是很复杂。

复位操作
softReset(); //Reset all configuration, threshold, and data registers to POR values
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函数代码如下

void MAX30105::softReset(void) {
  bitMask(MAX30105_MODECONFIG, MAX30105_RESET_MASK, MAX30105_RESET);

  // Poll for bit to clear, reset is then complete
  // Timeout after 100ms
  unsigned long startTime = millis();
  while (millis() - startTime < 100)
  {
    uint8_t response = readRegister8(_i2caddr, MAX30105_MODECONFIG);
    if ((response & MAX30105_RESET) == 0) break; //We're done!
    delay(1); //Let's not over burden the I2C bus
  }
}
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这个bitMask函数还是挺有意思的,之前做这类操作的时候没有想过用这种方法。

后面的部分就是读取了esp32启动以来的毫秒数,然后做循环,判断这个位是不是设置成功了。
就是等待100毫秒,看复位成功了没有。

话说这个操作方式确实比较精准,误差不会太大。

void MAX30105::bitMask

这个函数是一个位操作的函数,控制一位或者几位的bit的赋值。

代码如下:

void MAX30105::bitMask(uint8_t reg, uint8_t mask, uint8_t thing)
{
  // Grab current register context
  uint8_t originalContents = readRegister8(_i2caddr, reg);

  // Zero-out the portions of the register we're interested in
  originalContents = originalContents & mask;

  // Change contents
  writeRegister8(_i2caddr, reg, originalContents | thing);
}
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操作流程如下:

  1. 读取该地址的值
  2. 把读取到的数据和mask做与操作
  3. 写入第二步得到的数值与thing的或运算的值

这个操作一开始看,感觉有点傻,为啥不直接传输thing,然后在里面进行取反操作,何必多次一举,看了其他调用这个函数的代码,我大概搞清楚了。
这个操作不是单纯的对一位bit进行操作,而是对多位进行操作,打个比方
现在有第0位到第2位的bit是代表一个模式设置,这个模式有101,110,111三种。那么就可以传输一个二进制是1111 1000的mask,那与读取出来的值进行与操作之后,就把第0位到第2位的数据清零了,这时thing再传递三种模式的其中一种。这样就可以做到任意位数的赋值,这种方式还挺巧妙的。

但是也能感觉到作者在写mark的数据定义的时候挺烦的,一会2进制赋值,一会16进制赋值。

FIFO配置

FIFO就可以想象成一个队列,先进先出,用于缓存数据的。

代码如下

if (sampleAverage == 1) setFIFOAverage(MAX30105_SAMPLEAVG_1); //No averaging per FIFO record
  else if (sampleAverage == 2) setFIFOAverage(MAX30105_SAMPLEAVG_2);
  else if (sampleAverage == 4) setFIFOAverage(MAX30105_SAMPLEAVG_4);
  else if (sampleAverage == 8) setFIFOAverage(MAX30105_SAMPLEAVG_8);
  else if (sampleAverage == 16) setFIFOAverage(MAX30105_SAMPLEAVG_16);
  else if (sampleAverage == 32) setFIFOAverage(MAX30105_SAMPLEAVG_32);
  else setFIFOAverage(MAX30105_SAMPLEAVG_4);
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setFIFOAverage函数中只有bitMask(MAX30105_FIFOCONFIG, MAX30105_SAMPLEAVG_MASK, numberOfSamples);这一段代码

定义的代码如下

static const uint8_t MAX30105_FIFOCONFIG = 		0x08;

static const uint8_t MAX30105_SAMPLEAVG_MASK =	(byte)~0b11100000;
static const uint8_t MAX30105_SAMPLEAVG_1 = 	0x00;
static const uint8_t MAX30105_SAMPLEAVG_2 = 	0x20;
static const uint8_t MAX30105_SAMPLEAVG_4 = 	0x40;
static const uint8_t MAX30105_SAMPLEAVG_8 = 	0x60;
static const uint8_t MAX30105_SAMPLEAVG_16 = 	0x80;
static const uint8_t MAX30105_SAMPLEAVG_32 = 	0xA0;
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具体表达了什么意思可以看前言里我写的文章里的FIFO配置章节,我在这里也做了部分引用

地址功能B7B6B5B4B3B2B1B0R/W
0x08FIFO配置SMP_AVE[2]SMP_AVE[1]SMP_AVE[0]FIFO_ROL LOVER_ENFIFO_A_FULL[3]FIFO_A_FULL[2]FIFO_A_FULL[1]FIFO_A_FULL[0]RW

SMP_AVE:平均值,为了减少数据吞吐量,通过设置这个寄存器,相邻的样本(在每个单独的通道中)可以在芯片上进行平均和抽取。

SMP_AVE平均量
0001(不平均)
0012
0104
0118
10016
10132
11032
11132

FIFO_ROL LOVER_EN:FIFO被填满之后的控制。如果是0,在你读取之前都不会更新,如果是1,会更新覆盖之前的数据

更新使能

这其实也是FIFO的设置,当设置为1时如果FIFO中的数据满了,那么就会覆盖老的数据,设置为0则不会覆盖。

enableFIFORollover(); //Allow FIFO to wrap/roll over
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内部也就是调用了bitMask,代码如下

void MAX30105::enableFIFORollover(void) {
  bitMask(MAX30105_FIFOCONFIG, MAX30105_ROLLOVER_MASK, MAX30105_ROLLOVER_ENABLE);
}
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同上,可以看前言里的MAX30102分析。

可以看出来,设置的过程是按照功能划分的,更新使能和FIFO配置都是一个寄存器里的内容,却分成了两个部分来写。可读性比较好,但是执行效率就不怎么高了。

LED设置

设置红光和红外光,三种模式,同上,可以看前言里的MAX30102分析。

  if (ledMode == 3) setLEDMode(MAX30105_MODE_MULTILED); //Watch all three LED channels
  else if (ledMode == 2) setLEDMode(MAX30105_MODE_REDIRONLY); //Red and IR
  else setLEDMode(MAX30105_MODE_REDONLY); //Red only
  activeLEDs = ledMode; //Used to control how many bytes to read from FIFO buffer
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ADC检测设置

设置ADC的采样范围,具体参数,可以看前言里的MAX30102分析。

  if(adcRange < 4096) setADCRange(MAX30105_ADCRANGE_2048); //7.81pA per LSB
  else if(adcRange < 8192) setADCRange(MAX30105_ADCRANGE_4096); //15.63pA per LSB
  else if(adcRange < 16384) setADCRange(MAX30105_ADCRANGE_8192); //31.25pA per LSB
  else if(adcRange == 16384) setADCRange(MAX30105_ADCRANGE_16384); //62.5pA per LSB
  else setADCRange(MAX30105_ADCRANGE_2048);
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SpO2采样率控制

采样率和脉冲宽度是相关的,因为采样率设置了脉冲宽度时间的上限。如果用户选择的采样率对于所选LED_PW设置来说太高,则将尽可能高的采样率编程到寄存器中。具体参数,可以看前言里的MAX30102分析。

  if (sampleRate < 100) setSampleRate(MAX30105_SAMPLERATE_50); //Take 50 samples per second
  else if (sampleRate < 200) setSampleRate(MAX30105_SAMPLERATE_100);
  else if (sampleRate < 400) setSampleRate(MAX30105_SAMPLERATE_200);
  else if (sampleRate < 800) setSampleRate(MAX30105_SAMPLERATE_400);
  else if (sampleRate < 1000) setSampleRate(MAX30105_SAMPLERATE_800);
  else if (sampleRate < 1600) setSampleRate(MAX30105_SAMPLERATE_1000);
  else if (sampleRate < 3200) setSampleRate(MAX30105_SAMPLERATE_1600);
  else if (sampleRate == 3200) setSampleRate(MAX30105_SAMPLERATE_3200);
  else setSampleRate(MAX30105_SAMPLERATE_50);

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设置LED脉宽控制和ADC分辨率

这些位设置LED脉冲宽度(IR和Red具有相同的脉冲宽度),因此间接设置每个样本中ADC的积分时间。ADC分辨率与积分时间直接相关。具体参数,可以看前言里的MAX30102分析。

  if (pulseWidth < 118) setPulseWidth(MAX30105_PULSEWIDTH_69); //Page 26, Gets us 15 bit resolution
  else if (pulseWidth < 215) setPulseWidth(MAX30105_PULSEWIDTH_118); //16 bit resolution
  else if (pulseWidth < 411) setPulseWidth(MAX30105_PULSEWIDTH_215); //17 bit resolution
  else if (pulseWidth == 411) setPulseWidth(MAX30105_PULSEWIDTH_411); //18 bit resolution
  else setPulseWidth(MAX30105_PULSEWIDTH_69);
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LED脉冲宽度设置

设置脉冲宽度,具体参数,可以看前言里的MAX30102分析。

setPulseAmplitudeRed(powerLevel);
setPulseAmplitudeIR(powerLevel);
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非MAX30102有效寄存器

这两个设置在MAX30102中是无效的,因为数据手册中这个地址的寄存器并没有分配功能,但是因为MAX30105是向下兼容的,所以MAX30102使用也不会出问题。

setPulseAmplitudeGreen(powerLevel);
setPulseAmplitudeProximity(powerLevel);
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多LED模式控制
 enableSlot(1, SLOT_RED_LED);
if (ledMode > 1) enableSlot(2, SLOT_IR_LED);
if (ledMode > 2) enableSlot(3, SLOT_GREEN_LED);
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void MAX30105::enableSlot(uint8_t slotNumber, uint8_t device) {

  uint8_t originalContents;

  switch (slotNumber) {
    case (1):
      bitMask(MAX30105_MULTILEDCONFIG1, MAX30105_SLOT1_MASK, device);
      break;
    case (2):
      bitMask(MAX30105_MULTILEDCONFIG1, MAX30105_SLOT2_MASK, device << 4);
      break;
    case (3):
      bitMask(MAX30105_MULTILEDCONFIG2, MAX30105_SLOT3_MASK, device);
      break;
    case (4):
      bitMask(MAX30105_MULTILEDCONFIG2, MAX30105_SLOT4_MASK, device << 4);
      break;
    default:
      //Shouldn't be here!
      break;
  }
}
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如果是MAX30102最大只可以设置到2。

清除FIFO

具体参数,可以看前言里的MAX30102分析。

clearFIFO(); //Reset the FIFO before we begin checking the sensor
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