bPi no spi

software/analogPressure/mcp3008BitBang.py

@@ -0,0 +1,109 @@
+#!/usr/bin/env python
+#
+# Bitbang'd SPI interface with an MCP3008 ADC device
+# MCP3008 is 8-channel 10-bit analog to digital converter
+#  Connections are:
+#     CLK => 18  
+#     DOUT => 23 (chip's data out, RPi's MISO)
+#     DIN => 24  (chip's data in, RPi's MOSI)
+#     CS => 25 
+
+import RPi.GPIO as GPIO
+import time
+import sys
+
+CLK = 11
+MISO = 9
+MOSI = 10
+CS0 = 8
+CS1 = 7
+
+def setupSpiPins(clkPin, misoPin, mosiPin, csPin):
+    ''' Set all pins as an output except MISO (Master Input, Slave Output)'''
+    GPIO.setup(clkPin, GPIO.OUT)
+    GPIO.setup(misoPin, GPIO.IN)
+    GPIO.setup(mosiPin, GPIO.OUT)
+    GPIO.setup(csPin, GPIO.OUT)
+     
+
+def readAdc(channel, clkPin, misoPin, mosiPin, csPin):
+    if (channel < 0) or (channel > 7):
+        print "Invalid ADC Channel number, must be between [0,7]"
+        return -1
+        
+    # Datasheet says chip select must be pulled high between conversions
+    GPIO.output(csPin, GPIO.HIGH)
+    
+    # Start the read with both clock and chip select low
+    GPIO.output(csPin, GPIO.LOW)
+    GPIO.output(clkPin, GPIO.HIGH)
+    
+    # read command is:
+    # start bit = 1
+    # single-ended comparison = 1 (vs. pseudo-differential)
+    # channel num bit 2
+    # channel num bit 1
+    # channel num bit 0 (LSB)
+    read_command = 0x18
+    read_command |= channel
+    
+    sendBits(read_command, 5, clkPin, mosiPin)
+    
+    adcValue = recvBits(12, clkPin, misoPin)
+    
+    # Set chip select high to end the read
+    GPIO.output(csPin, GPIO.HIGH)
+  
+    return adcValue
+    
+def sendBits(data, numBits, clkPin, mosiPin):
+    ''' Sends 1 Byte or less of data'''
+    
+    data <<= (8 - numBits)
+    
+    for bit in range(numBits):
+        # Set RPi's output bit high or low depending on highest bit of data field
+        if data & 0x80:
+            GPIO.output(mosiPin, GPIO.HIGH)
+        else:
+            GPIO.output(mosiPin, GPIO.LOW)
+        
+        # Advance data to the next bit
+        data <<= 1
+        
+        # Pulse the clock pin HIGH then immediately low
+        GPIO.output(clkPin, GPIO.HIGH)
+        GPIO.output(clkPin, GPIO.LOW)
+
+def recvBits(numBits, clkPin, misoPin):
+    '''Receives arbitrary number of bits'''
+    retVal = 0
+    
+    for bit in range(numBits):
+        # Pulse clock pin 
+        GPIO.output(clkPin, GPIO.HIGH)
+        GPIO.output(clkPin, GPIO.LOW)
+        
+        # Read 1 data bit in
+        if GPIO.input(misoPin):
+            retVal |= 0x1
+        
+        # Advance input to next bit
+        retVal <<= 1
+    
+    # Divide by two to drop the NULL bit
+    return (retVal/2)
+    
+    
+if __name__ == '__main__':
+    try:
+        GPIO.setmode(GPIO.BCM)
+        setupSpiPins(CLK, MISO, MOSI, CS)
+    
+        while True:
+            val = readAdc(0, CLK, MISO, MOSI, CS)
+            print "ADC Result: ", str(val)
+            time.sleep(5)
+    except KeyboardInterrupt:
+        GPIO.cleanup()
+        sys.exit(0)

software/install.md

@@ -7,7 +7,7 @@ on Ubuntu / Debian
 ``` bash
 sudo apt update
 sudo apt upgrade -y
-sudo apt install python3 python3-pip
+sudo apt install python3-dev python3-pip
 python3 -m pip -U pip setuptools
 ```
 
@@ -22,7 +22,7 @@ python3 -m pip install PyQt5 PyQt5-tools
 on Ubuntu / Debian
 
 ``` bash
-sudo apt-get install bluez bluez-utils python3-bluez
+sudo apt-get install bluez bluez-tools python3-bluez
 ```
 
 ## SPI for Python