[WIP] First demo

README.md

@@ -1,3 +1,21 @@
 # raspicar
 
 Get and Display car sensors
+
+## Requirements
+
+### Hardware
+
+- Raspberry Pi Zero or other Raspberry Pi version (3 or 4)
+- [Optional] UBEC DC/DC Step-Down (Buck) Converter - 5V @ 3A output
+- Adafruit 0.56" 4-Digit 7-Segment Display w/I2C Backpack
+- Voltage sensor (tested with Grove - Voltage Divider)
+- MCP3008 - 8-Channel 10-Bit ADC With SPI Interface
+- Momentary switch button
+
+### Software
+
+- Raspios
+- pip3 (sudo apt install python3-pip)
+- HT16K33 Library (sudo pip3 install adafruit-circuitpython-ht16k33)
+- Pillow Library (sudo apt install python3-pil)

raspicar.py

@@ -0,0 +1,123 @@
+import time
+import board
+import RPi.GPIO as GPIO
+
+from datetime import datetime
+from adafruit_ht16k33.segments import Seg7x4
+
+# ADC configuration
+CLK = 11
+MISO = 9
+MOSI = 10
+CS = 8
+CHANNEL = 0 # By default read sensor 0
+
+# Display configuration
+i2c = board.I2C()
+display = Seg7x4(i2c)
+
+# Button
+BUTTON = 5 # GPIO5
+
+# Function called on push button (change sensor)
+def handlePushButton(button):
+    global CHANNEL
+    CHANNEL += 1
+    if ( CHANNEL > 8 ):
+        CHANNEL = 0
+
+    display.print("  :"+str(CHANNEL)+"-")
+
+
+# Init program
+def init():
+    # Set display
+    display.brightness = 1
+    display.blink_rate = 0 # Between 0 and 3
+
+    GPIO.setwarnings(False)
+    GPIO.setmode(GPIO.BCM)
+
+    GPIO.setup(BUTTON, GPIO.IN, pull_up_down=GPIO.PUD_UP)
+    GPIO.setup(MOSI, GPIO.OUT)
+    GPIO.setup(MISO, GPIO.IN)
+    GPIO.setup(CLK, GPIO.OUT)
+    GPIO.setup(CS, GPIO.OUT)
+
+    # Add button event
+    GPIO.add_event_detect(BUTTON, GPIO.FALLING, callback=handlePushButton, bouncetime=250)
+
+    pass
+
+
+#read SPI data from MCP3008(or MCP3204) chip,8 possible adc's (0 thru 7)
+def readadc(adcnum, clockpin, mosipin, misopin, cspin):
+    if ((adcnum > 7) or (adcnum < 0)):
+        return -1
+
+    GPIO.output(cspin, True)
+    GPIO.output(clockpin, False)  # start clock low
+    GPIO.output(cspin, False)     # bring CS low
+
+    commandout = adcnum
+    commandout |= 0x18  # start bit + single-ended bit
+    commandout <<= 3    # we only need to send 5 bits here
+    for i in range(5):
+        if (commandout & 0x80):
+            GPIO.output(mosipin, True)
+        else:
+            GPIO.output(mosipin, False)
+
+        commandout <<= 1
+        GPIO.output(clockpin, True)
+        GPIO.output(clockpin, False)
+
+    adcout = 0
+
+    # read in one empty bit, one null bit and 10 ADC bits
+    for i in range(12):
+        GPIO.output(clockpin, True)
+        GPIO.output(clockpin, False)
+        adcout <<= 1
+        if (GPIO.input(misopin)):
+            adcout |= 0x1
+
+    GPIO.output(cspin, True)
+
+    #adcout >>= 1       # first bit is 'null' so drop it
+    return adcout
+
+
+# Main programm
+def main():
+    init()
+    time.sleep(2)
+    print("Let's go!")
+
+    while True:
+        if ( CHANNEL == 8 ): # Last sensor => clock mode
+            now = datetime.now()
+            printableValue = now.strftime("%H:%M")
+        else:
+            # Get current sensor value
+            ad_value = readadc(CHANNEL, CLK, MOSI, MISO, CS)
+            value = ad_value*(3.3/1024)*5
+            # Format value with 2 decimals
+            printableValue = f"{value:.02f}"
+
+        # Clear display
+        display.fill(0)
+        # Print new value
+        display.print(str(printableValue))
+
+        # Wait between next loop
+        time.sleep(10)
+
+
+if __name__ =='__main__':
+    try:
+        main()
+    except KeyboardInterrupt:
+        pass
+
+print("GoodBye!")