Extended version for use with TCA9548A and multiple AS5600

as5600_tca9548a.py

@@ -0,0 +1,144 @@
+#!/usr/bin/python3
+# Extended version of Matthias Wandel AS5600 example code:
+# https://github.com/Matthias-Wandel/AS5600-Raspberry-Pi-Python/blob/master/as5600.py
+#
+# This extended version is for use with TCA9548A multiple(xer) AS5600 encoders
+# https://www.ti.com/lit/ds/symlink/tca9548a.pdf
+# https://www.mouser.com/pdfdocs/AMS_AS5600_Datasheet_EN.PDF
+#
+# Usage: python3 as5600_tca9548a.py <channel> or empty
+# No given argument will disable TCA9548A switching and read from 0x36 directly
+# channel is a number from 0 to 7, which will select the TCA9548A channel
+#
+# Very simple code to read AS5600 magnetic encoder with Python
+# on raspberry pi
+#
+# Requires Python smbus module.  Get it using:
+#     sudo apt-get install python3-smbus
+#
+# Make sure Pi's I2c is enabled using
+#     sudo raspi-config
+#
+# Connect Pi's ground to GND and DIR pins
+# Connect Pi's 3.3 volts to VCC on AS5600
+# Connect Pi's I2c SCL (pin 5) to AS5600 SCL pin
+# Connect Pi's I2c SDA (pin 5) to AS5600 SDA pin
+#
+# Watchout: use a level shifter if you are using 5V AS5600
+# ======================================================================
+# bash commands:
+#
+# read i2c-bus:                sudo i2cdetect -y 1
+# set TCA9548A switching off:  sudo i2cset -y 1 0x70 0x00
+#
+# set TCA9548A channel-0:      sudo i2cset -y 1 0x70 0x01
+# set TCA9548A channel-1:      sudo i2cset -y 1 0x70 0x02
+#
+# read AS5600 raw angle:       sudo i2cget -y 1 0x36 0x0C
+# read AS5600 magnitude:       sudo i2cget -y 1 0x36 0x1B
+
+import smbus, time, sys, math
+
+DEVICE_TCA9548A = 0x70  # TCA9548A default address (0x70-0x77)
+DEVICE_AS5600 = 0x36    # AS5600 fixed address, AS5600L version is changeable
+bus = smbus.SMBus(1)
+
+# function TCA9548A channel switching
+def SelectTCAChannel(channel):
+    if channel < 0 or channel > 7:
+        raise ValueError("channel must be between 0 and 7 ")
+    bus.write_byte(DEVICE_TCA9548A, 1 << channel)
+
+#=====================================================================
+# Code to read AS5600.  x lines of python is all it takes.
+def ReadRawAngle(): # Read angle (0-360 represented as 0-4096)
+    read_bytes = bus.read_i2c_block_data(DEVICE_AS5600, 0x0C, 2)
+    return (read_bytes[0] << 8) | read_bytes[1]
+
+def ReadMagnitude(): # Read magnetism magnitude
+    read_bytes = bus.read_i2c_block_data(DEVICE_AS5600, 0x1B, 2)
+    return (read_bytes[0] << 8) | read_bytes[1]
+
+#=====================================================================
+xcenter = 40  # Assume center of text screen is 80 across, 24 down.
+ycenter = 12  # if your screen is 80x50, change to 40 and 25.
+
+def MoveCursor(x, y):
+    print("\033[%d;%dH" % (y, x), end="")
+
+# if there is a command line argument, it is the TCA9548A channel
+# and the TCA9548A switching is activated
+try:
+    if len(sys.argv) != 2:
+        print("no channel given, direct access to AS5600")
+        #DisableTCAChannels()
+        current_channel = None  # no channel
+    else:
+        current_channel = int(sys.argv[1])
+        if current_channel < 0 or current_channel > 7:
+            raise ValueError
+        SelectTCAChannel(current_channel)
+except ValueError:
+    print("error: channel must be between 0 and 7")
+    sys.exit(1)
+
+# Clear screen
+print("\033[2J", end="")
+
+# Draw x and y axis on screen
+for a in range(-ycenter, ycenter):
+    MoveCursor(xcenter, ycenter + a)
+    print("|", end="")
+
+for a in range(-xcenter, xcenter):
+    MoveCursor(xcenter + a, ycenter)
+    print("-")
+
+histlen = 400
+hist_index = 0
+hist = [(0, 0)] * histlen
+
+# TCA9548A-channel switching
+if current_channel is not None:
+    SelectTCAChannel(current_channel)
+
+while True:
+    # read
+    try:
+        raw_angle = ReadRawAngle()
+        magnitude = ReadMagnitude()
+
+        MoveCursor(0, 0)
+        if current_channel is not None:
+            print("Multiplexer Channel: %d | Raw angle: %4d" % (current_channel, raw_angle), "m=%4d" % (magnitude), "%6.2f deg  " % (raw_angle * 360.0 / 4096))
+        else:
+            print("Direct Access. Raw angle: %4d" % (raw_angle), "m=%4d" % (magnitude), "%6.2f deg  " % (raw_angle * 360.0 / 4096))
+
+        # X- und Y-Position berechnen und auf dem Bildschirm darstellen
+        xymag = magnitude / 1024.0
+        cx = int(xcenter + xcenter * xymag * math.cos(raw_angle * math.pi / 2048))
+        cy = int(ycenter + ycenter * xymag * math.sin(raw_angle * math.pi / 2048))
+
+        # Alte Markierung löschen (bis zu 400 auf dem Bildschirm)
+        oldpos = hist[hist_index]
+        MoveCursor(*oldpos)
+        if oldpos[0] == xcenter:
+            print("|", end="")
+        elif oldpos[1] == ycenter:
+            print("-", end="")
+        else:
+            print(" ", end="")
+
+        # Save new mark positon in array
+        hist[hist_index] = (cx, cy)
+        hist_index += 1
+        if hist_index >= histlen:
+            hist_index = 0
+
+        # Draw a '#' at the computed X,Y coordinate
+        MoveCursor(cx, cy)
+        print("#", end="")
+
+    except Exception as e:
+        MoveCursor(0, 0)
+        print(f"error while reading: {e}", end="")