MPR121 Touch IC Based Keypad Input Module (#5103)

Implements an input driver utilising the MPR121 Touch IC and is compatible with common MPR121 keypad PCB's.

- Implements a "candybar" phone style 12-key keypad
  - multiple taps to rotate through the character set
  - longpress for navigation keys
  - keymap to allow arbitrary routing of MPR121 pin to button configuration
  - extendable to other key functions
- Integrates with the existing kbI2cBase implementation
- Works with CannedMessageModule Freetext mode
- Can be used with common MPR121 boards, such as https://www.amazon.com/MPR121-Capacitive-Keyboard-Buttons-Sensitive/dp/B083R89CHB/ref=sr_1_6
- Of use for PCB based radios, where some form of low surface area low component freetext input is required, but also without consuming too many IO pins.
- Tested on a T3S3 connected to Wire1 (Second) interface.
  - Demonstration of functionality: https://youtu.be/UI6QP6nGvhY

src/configuration.h

@@ -114,6 +114,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #define CARDKB_ADDR 0x5F
 #define TDECK_KB_ADDR 0x55
 #define BBQ10_KB_ADDR 0x1F
+#define MPR121_KB_ADDR 0x5A
 
 // -----------------------------------------------------------------------------
 // SENSOR

src/detect/ScanI2C.cpp

@@ -31,8 +31,8 @@ ScanI2C::FoundDevice ScanI2C::firstRTC() const
 
 ScanI2C::FoundDevice ScanI2C::firstKeyboard() const
 {
-    ScanI2C::DeviceType types[] = {CARDKB, TDECKKB, BBQ10KB, RAK14004};
-    return firstOfOrNONE(4, types);
+    ScanI2C::DeviceType types[] = {CARDKB, TDECKKB, BBQ10KB, RAK14004, MPR121KB};
+    return firstOfOrNONE(5, types);
 }
 
 ScanI2C::FoundDevice ScanI2C::firstAccelerometer() const

src/detect/ScanI2C.h

@@ -61,7 +61,8 @@ class ScanI2C
         STK8BAXX,
         ICM20948,
         MAX30102,
-        TPS65233
+        TPS65233,
+        MPR121KB
     } DeviceType;
 
     // typedef uint8_t DeviceAddress;

src/detect/ScanI2CTwoWire.cpp

@@ -243,6 +243,7 @@ void ScanI2CTwoWire::scanPort(I2CPort port, uint8_t *address, uint8_t asize)
 
                 SCAN_SIMPLE_CASE(TDECK_KB_ADDR, TDECKKB, "T-Deck keyboard found");
                 SCAN_SIMPLE_CASE(BBQ10_KB_ADDR, BBQ10KB, "BB Q10 keyboard found");
+
                 SCAN_SIMPLE_CASE(ST7567_ADDRESS, SCREEN_ST7567, "st7567 display found");
 #ifdef HAS_NCP5623
                 SCAN_SIMPLE_CASE(NCP5623_ADDR, NCP5623, "NCP5623 RGB LED found");
@@ -408,7 +409,17 @@ void ScanI2CTwoWire::scanPort(I2CPort port, uint8_t *address, uint8_t asize)
 #ifdef HAS_TPS65233
                 SCAN_SIMPLE_CASE(TPS65233_ADDR, TPS65233, "TPS65233 BIAS-T found");
 #endif
-                SCAN_SIMPLE_CASE(MLX90614_ADDR_DEF, MLX90614, "MLX90614 IR temp sensor found");
+
+            case MLX90614_ADDR_DEF:
+                registerValue = getRegisterValue(ScanI2CTwoWire::RegisterLocation(addr, 0x0e), 1);
+                if (registerValue == 0x5a) {
+                    type = MLX90614;
+                    LOG_INFO("MLX90614 IR temp sensor found");
+                } else {
+                    type = MPR121KB;
+                    LOG_INFO("MPR121KB keyboard found");
+                }
+                break;
 
             case ICM20948_ADDR:     // same as BMX160_ADDR
             case ICM20948_ADDR_ALT: // same as MPU6050_ADDR