adding demo code for PCA9546

Adding demo code since it will be in two guides (breakout and stemma breakout)

PCA9546_Demos/PCA9546_I2C_Scanner/PCA9546_I2C_Scanner.ino

@@ -0,0 +1,53 @@
+// SPDX-FileCopyrightText: 2023 Liz Clark for Adafruit Industries
+//
+// SPDX-License-Identifier: MIT
+/**
+ * PCA9546 I2CScanner.ino -- I2C bus scanner for Arduino
+ *
+ * Based on https://playground.arduino.cc/Main/I2cScanner/
+ *
+ */
+
+#include "Wire.h"
+
+#define PCAADDR 0x70
+
+void pcaselect(uint8_t i) {
+  if (i > 3) return;
+ 
+  Wire.beginTransmission(PCAADDR);
+  Wire.write(1 << i);
+  Wire.endTransmission();  
+}
+
+
+// standard Arduino setup()
+void setup()
+{
+    while (!Serial);
+    delay(1000);
+
+    Wire.begin();
+    
+    Serial.begin(115200);
+    Serial.println("\nPCAScanner ready!");
+    
+    for (uint8_t t=0; t<4; t++) {
+      pcaselect(t);
+      Serial.print("PCA Port #"); Serial.println(t);
+
+      for (uint8_t addr = 0; addr<=127; addr++) {
+        if (addr == PCAADDR) continue;
+
+        Wire.beginTransmission(addr);
+        if (!Wire.endTransmission()) {
+          Serial.print("Found I2C 0x");  Serial.println(addr,HEX);
+        }
+      }
+    }
+    Serial.println("\ndone");
+}
+
+void loop() 
+{
+}

PCA9546_Demos/PCA9546_MultiSensors/PCA9546_MultiSensors.ino

@@ -0,0 +1,117 @@
+// SPDX-FileCopyrightText: 2023 Liz Clark for Adafruit Industries
+//
+// SPDX-License-Identifier: MIT
+/**
+ * PCA9546 I2C Multi Sensor Example
+ *
+ * Using two VL53L4CD sensors on ports 0 and 1
+ *
+ */
+
+#include <Arduino.h>
+#include <Wire.h>
+#include <vl53l4cd_class.h>
+#include <string.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <assert.h>
+
+#define PCAADDR 0x70
+#define DEV_I2C Wire
+
+#define SerialPort Serial
+
+// create two instances of the sensor
+VL53L4CD tof1(&DEV_I2C, A1);
+VL53L4CD tof2(&DEV_I2C, A1);
+
+void pcaselect(uint8_t i) {
+  if (i > 3) return;
+ 
+  Wire.beginTransmission(PCAADDR);
+  Wire.write(1 << i);
+  Wire.endTransmission();  
+}
+
+// standard Arduino setup()
+void setup()
+{
+    while (!Serial);
+    delay(1000);
+
+    Wire.begin();
+    
+    Serial.begin(115200);
+    Serial.println("\nMultiSensor PCA9546");
+    
+    // define the port on the PCA9546 for the first sensor
+    pcaselect(0);
+    // setup the first sensor
+    tof1.begin();
+    tof1.VL53L4CD_Off();
+    tof1.InitSensor();
+    tof1.VL53L4CD_SetRangeTiming(200, 0);
+    tof1.VL53L4CD_StartRanging();
+  
+    // define the port on the PCA9546 for the 2nd sensor
+    pcaselect(1);
+    
+    // setup the 2nd sensor
+    tof2.begin();
+    tof2.VL53L4CD_Off();
+    tof2.InitSensor();
+    tof2.VL53L4CD_SetRangeTiming(200, 0);
+    tof2.VL53L4CD_StartRanging();
+      
+}
+
+void loop() 
+{
+  uint8_t NewDataReady = 0;
+  VL53L4CD_Result_t results;
+  uint8_t status;
+  char report[64];
+  
+  // define port on the PCA9546
+  pcaselect(0);
+
+  // loop for time of flight sensor 1
+  do {
+    status = tof1.VL53L4CD_CheckForDataReady(&NewDataReady);
+  } while (!NewDataReady);
+
+  if ((!status) && (NewDataReady != 0)) {
+    // (Mandatory) Clear HW interrupt to restart measurements
+    tof1.VL53L4CD_ClearInterrupt();
+
+    // Read measured distance. RangeStatus = 0 means valid data
+    tof1.VL53L4CD_GetResult(&results);
+    snprintf(report, sizeof(report), "ToF 1 - Status = %3u, Distance = %5u mm, Signal = %6u kcps/spad\r\n",
+             results.range_status,
+             results.distance_mm,
+             results.signal_per_spad_kcps);
+    SerialPort.println(report);
+  }
+
+  // define port on PCA9546
+  pcaselect(1);
+
+  // loop for time of flight sensor 2
+  do {
+    status = tof2.VL53L4CD_CheckForDataReady(&NewDataReady);
+  } while (!NewDataReady);
+
+  if ((!status) && (NewDataReady != 0)) {
+    // (Mandatory) Clear HW interrupt to restart measurements
+    tof2.VL53L4CD_ClearInterrupt();
+
+    // Read measured distance. RangeStatus = 0 means valid data
+    tof2.VL53L4CD_GetResult(&results);
+    snprintf(report, sizeof(report), "ToF 2 - Status = %3u, Distance = %5u mm, Signal = %6u kcps/spad\r\n",
+             results.range_status,
+             results.distance_mm,
+             results.signal_per_spad_kcps);
+    SerialPort.println(report);
+  }
+}