如何从 Nonin Xpod PulseOxy 传感器获取数据到 Raspberry Pi

Question

我使用的是 Raspberry Pi 2 板，并且已将 Nonin Xpod PulseOxy 传感器连接到它。我在 python 脚本中使用 PyUSB 模块来访问传感器的基本数据，如供应商 ID、产品 ID 等。我无法设置设备的配置并继续收集读数。我尝试安装 http://www.ftdichip.com/ 为 Raspberry Pi 提供的 ftdi 驱动程序。但是 d2xx 模块没有被导入到我的 python 脚本中。 我是为设备编写代码的新手。请帮助我了解如何进行。

我厌倦了以下内容：

import usb.core
import usb.util
dev = usb.core.find(idVendor=0x0424, idProduct=0x9514)
dev.set_configuration()

我在设置配置中遇到错误。

Traceback (most recent call last):
File "s1.py", line 18, in <module>
main()
File "s1.py", line 13, in main
dev.set_configuration()
File "/usr/local/lib/python2.7/dist-packages/usb/core.py", line 799, in         set_configuration
self._ctx.managed_set_configuration(self, configuration)
File "/usr/local/lib/python2.7/dist-packages/usb/core.py", line 128, in  managed_set_configuration
self.backend.set_configuration(self.handle, cfg.bConfigurationValue)
File "/usr/local/lib/python2.7/dist-packages/usb/backend/libusb0.py", line   439, in set_configuration
_check(_lib.usb_set_configuration(dev_handle, config_value))
File "/usr/local/lib/python2.7/dist-packages/usb/backend/libusb0.py", line 380, in _check
raise USBError(errmsg, ret)
usb.core.USBError: [Errno None] could not set config 1: Device or resource busy 

传感器的数据表是Nonin Xpod 3012LP

首先感谢您的回答。我已经尝试了 libftd2XX 安装，使用命令 make -B 后出现以下错误

for n in BitMode EEPROM/erase EEPROM/read EEPROM/write EEPROM/user/read    EEPROM/user/size EEPROM/user/write Events LargeRead MultiThread SetVIDPID Simple   Timeouts ; do make -C $n || exit 1; done
make[1]: Entering directory '/home/pi/iiitd/release/examples/BitMode'
make[1]: Nothing to be done for 'all'.
make[1]: Leaving directory '/home/pi/iiitd/release/examples/BitMode'
make[1]: Entering directory '/home/pi/iiitd/release/examples/EEPROM/erase'
make[1]: Nothing to be done for 'all'.
make[1]: Leaving directory '/home/pi/iiitd/release/examples/EEPROM/erase'
make[1]: Entering directory '/home/pi/iiitd/release/examples/EEPROM/read'
make[1]: Nothing to be done for 'all'.
make[1]: Leaving directory '/home/pi/iiitd/release/examples/EEPROM/read'
make[1]: Entering directory '/home/pi/iiitd/release/examples/EEPROM/write'
make[1]: Nothing to be done for 'all'.
make[1]: Leaving directory '/home/pi/iiitd/release/examples/EEPROM/write'
make[1]: Entering directory    '/home/pi/iiitd/release/examples/EEPROM/user/read'
make[1]: Nothing to be done for 'all'.
make[1]: Leaving directory '/home/pi/iiitd/release/examples/EEPROM/user/read'
make[1]: Entering directory '/home/pi/iiitd/release/examples/EEPROM/user/size'
make[1]: Nothing to be done for 'all'.
make[1]: Leaving directory '/home/pi/iiitd/release/examples/EEPROM/user/size'
make[1]: Entering directory '/home/pi/iiitd/release/examples/EEPROM/user/write'
make[1]: Nothing to be done for 'all'.
make[1]: Leaving directory '/home/pi/iiitd/release/examples/EEPROM/user/write'
make[1]: Entering directory '/home/pi/iiitd/release/examples/Events'
make[1]: Nothing to be done for 'all'.
make[1]: Leaving directory '/home/pi/iiitd/release/examples/Events'
make[1]: Entering directory '/home/pi/iiitd/release/examples/LargeRead'
make[1]: Nothing to be done for 'all'.
make[1]: Leaving directory '/home/pi/iiitd/release/examples/LargeRead'
make[1]: Entering directory '/home/pi/iiitd/release/examples/MultiThread'
gcc main.c -o multi -Wall -Wextra -L. -lftd2xx -Wl,-rpath /usr/local/lib
/usr/bin/ld: /tmp/ccStfEVz.o: undefined reference to symbol    'pthread_join@@GLIBC_2.4'
//lib/arm-linux-gnueabihf/libpthread.so.0: error adding symbols: DSO missing    from command line
collect2: ld returned 1 exit status
Makefile:9: recipe for target 'multi' failed
make[1]: *** [multi] Error 1
make[1]: Leaving directory '/home/pi/iiitd/release/examples/MultiThread'
Makefile:11: recipe for target 'subdirs' failed
make: *** [subdirs] Error 1

Answer 1

我没有使用过 Nonin Xpod PulseOxy 传感器，但现在还不清楚它的接口。如果有用于交流的数据表，请发布。

如果设备显示为虚拟 com 端口，则 Raspberry PI 应该已准备好库，因此从 Python 中，pySerial 应该可以工作。

如果您需要使用 FTDI D2XX 库，请先安装 native library first（直接链接）。详情可查看here 并查看readme，尤其是这部分：

> If the message "FT_Open failed" appears:
>     Perhaps the kernel automatically loaded another driver for the 
>     FTDI USB device.
> 
>     `sudo lsmod`
> 
>     If "ftdi_sio" is listed:
>         Unload it (and its helper module, usbserial), as follows.
> 
>         `sudo rmmod ftdi_sio`
>         `sudo rmmod usbserial`
> 
>     Otherwise, it's possible that libftd2xx does not recognise your 
>     device's Vendor and Product Identifiers.  Call FT_SetVIDPID before
>     calling FT_Open/FT_OpenEx/FT_ListDevices.

我发现 Raspberry PI 默认加载 ftdi_sio 和 usbserial 驱动程序，因此必须先禁用这些驱动程序，然后才能使用 D2XX 库列出 FTDI 设备和详细信息。确保您可以首先编译他们的示例（库已正确链接）并运行他们的示例（您会看到列出的 FTDI 设备以及详细信息（例如 VID/PID/等））。只需导航到示例文件夹并使用make -b。 请注意，您可能需要将它们作为 sudo 运行。

如果上述工作正常，剩下的就是为 D2XX 库安装 Python 绑定。我用过这些ftd2xx Python bindings。设置应该是直截了当的。如果出现错误，请检查 ftd2xx 是否在正确路径中查找 .so 文件 (/usr/local/lib/libftd2xx.so)

安装后，您可以先尝试列出您的设备：

import ftd2xx
print ftd2xx.listDevices()

更新

看起来只有一个样本有错误，这取决于 pthreads 库。我现在尝试安装 ftd2xx python 库。 令人困惑的部分是普通串行应该可以工作：

"绿线 = 串行输出：9600 波特，8 个数据位，1 个起始位 （起始位 =0），一个停止位（停止位 = 1），无奇偶校验。”

您应该尝试使用串行库简单地读取数据：

import serial,time

def stringAsHex(s):
        return ":".join("{:02x}".format(ord(c)) for c in s)
sensor = serial.Serial('/dev/ttyACM0',timeout=1)#should default to 9600, 8 data bits, 1 stop bit, but feel free to use the constructor arguments to configure it

while True:
    data = sensor.read()
    if len(data) > 0:
        print "data str:",data,"hex:",stringAsHex(data)

请务必阅读有关 3.8v 到 3.3v 转换的说明以及基于所用电阻器的不同数据格式（在数据表的第 3 页和第 4 页）。

注意我使用的端口 (/dev/ttyACM0)：这通常是新的 Arduino 端口显示的内容。您必须检查您的设备是什么（可能显示为/dev/ttyUSB0，在将您的设备连接到 USB 端口之前和之后执行ls /dev/tty*）。

Answer 2

我终于能够使用以下代码从传感器获取数据：

import serial,time,sys
#returns non zero value if the bit is set
def testbit(value,bit):
return (value & 1 << bit)
#converts raw string to hexadecimal
def stringAsHex(s):
    return ":".join("{:02x}".format(ord(c)) for c in s)

#extract the information from a packet
def processpacket(p):
    msb=p[19][3]
    lsb=p[20][3]
    hr= ((msb<<7)|(lsb)) & 0x1ff
    emsb=p[21][3]
    elsb=p[22][3]
    ehr= ((emsb<<7)|(elsb)) & 0x1ff
    oxy=p[8][3]
    ol= oxy & 0x7f
    eoxy=p[16][3]
    eol= eoxy & 0x7f
    #print "Pulse Rate:", hr
    #print "Oxygen Level:", ol
    #if hr != 511 and  ol !=127 :
    if hr > 40 and hr < 200 and ol > 85 and ol < 127:
        #print "Pulse Rate:", hr
        #print "Extended Pulse Rate:",ehr
        #print "Oxygen Level:", ol
        #print "Extended Oxygen Level:",eol
        return hr,ol
     else:
        #print "Place your finger"
        hr=0
        ol=0
        return hr,ol

def readsensor(n):
    sd=[]
    val=[]
    sensor = serial.Serial('/dev/ttyUSB0',timeout=1,baudrate=9600)
    frame=[]
    fc=0
    packet=[]
    while True:
    frame=[]
            data = sensor.read()
            d=stringAsHex(data)
            intdata=int(d,16)
    #print 'loop 0'
            #print intdata 
            if intdata == 1:
                    data1 = sensor.read()
                    d1=stringAsHex(data1)
                    intdata1=int(d1,16)
                    #print 'if intdata == 1 sensor.read:',intdata1
                    tb = testbit(intdata1,0)
                    #print "test bit:", tb
                    if tb > 0 :
            #print 'packet began'
                            frame.append(intdata)
                            frame.append(intdata1)
                            fc = 2
            cnt = 0
            wc=0
                            while ( fc <= 125 ):
                wc = wc + 1
                #print 'while inside',wc
                                    data = sensor.read()
                                d=stringAsHex(data)
                                    intdata=int(d,16) 
                if len(frame)<=5:
                    frame.append(intdata)
                else:
                    #print 'oversized frame'
                    break
                #print 'fc',fc
                                fc = fc + 1


                if fc%5 == 0:
                    #print 'if fc%5 == 0'
                                            #print frame
                                            if frame[0] == 1:
                        cnt = cnt + 1
                        #print cnt
                                                    packet.append(frame)
                                                    frame=[]
                        #print 'frame empty'
                                            else:
                        #print 'else fc%5',fc
                        break

                if fc == 126:
                                            n = n - 1
                                            if n >= 0:
                                                    h,o= processpacket(packet)
                        sd.append([h,o])
                        #print sd
                                                    packet=[]
                        #print 'packet empty'
                                                    #print "***********Packet received***********"
                                                    fc = 1
                                            else:
                                                    return sd




        else:
            continue
    else:
        continue
print readsensor(20)

我意识到传感器正在提供字符。然后我将数据转换为整数并将其放入帧中并将帧组织成一个数据包（数据表中提到了帧和数据包的详细信息）。然后我从数据包中提取传感器读数。 帧和数据包是在python中使用列表实现的。