at42qt1070: Add additional functionality

Add functionality to read and set the low-power mode settings
Add functions to read and set the averaging factor per key
Add functions to read and set the adjecent key suppression (AKS) groups
Add a function to read the ID register
Add a sanity check to the constructor

Signed-off-by: Wouter van Verre <wouter.van.verre@intel.com>
Signed-off-by: Mihai Tudor Panu <mihai.tudor.panu@intel.com>

src/at42qt1070/at42qt1070.cxx

@@ -26,6 +26,7 @@
 #include <math.h>
 #include <iostream>
 #include <string>
+#include <stdexcept>
 
 #include "at42qt1070.h"
 
@@ -51,6 +52,10 @@ AT42QT1070::AT42QT1070(int bus, uint8_t address)
         return;
     }
 
+    if (readChipID() != 0x2E) {
+        throw std::runtime_error("Chip ID does not match the expected value (2Eh)");
+    }
+
     m_buttonStates = false;
     m_calibrating = false;
     m_overflow = false;
@@ -101,6 +106,12 @@ AT42QT1070::readWord(uint8_t reg)
     return mraa_i2c_read_word_data(m_i2c, reg);
 }
 
+uint8_t
+AT42QT1070::readChipID(void)
+{
+    return readByte(REG_CHIPID);
+}
+
 void
 AT42QT1070::updateState()
 {
@@ -129,6 +140,102 @@ AT42QT1070::updateState()
     }
 }
 
+uint8_t
+AT42QT1070::getLPMode(void)
+{
+    return readByte(REG_LP);
+}
+
+uint8_t
+AT42QT1070::setLPMode(uint8_t mode)
+{
+    writeByte(REG_LP, mode);
+
+    return getLPMode();
+}
+
+uint8_t
+AT42QT1070::getAVE(uint8_t key)
+{
+    uint8_t value, ave;
+
+    if (key > 6) {
+        throw std::invalid_argument("Only keys 0-6 are allowed");
+    }
+
+    value = readByte(REG_AVE0 + key);
+    ave = (value & 0xFC) >> 2;
+
+    return ave;
+}
+
+uint8_t
+AT42QT1070::setAVE(uint8_t key, uint8_t ave)
+{
+    uint8_t value;
+
+    if (key > 6) {
+        throw std::invalid_argument("Only keys 0-6 are allowed");
+    }
+
+    switch (ave) {
+        case 1:
+        case 2:
+        case 4:
+        case 8:
+        case 16:
+        case 32:
+            break;
+
+        default:
+            throw std::invalid_argument("Invalid averaging factor");
+    }
+
+    value = readByte(REG_AVE0 + key);
+    value = value & 0x03;
+    value = value | (ave << 2);
+    writeByte(REG_AVE0 + key, value);
+
+    return getAVE(key);
+}
+
+uint8_t
+AT42QT1070::getAKSGroup(uint8_t key)
+{
+    uint8_t value, aks;
+
+    if (key > 6) {
+        throw std::invalid_argument("Only keys 0-6 are allowed");
+    }
+
+    value = readByte(REG_AVE0 + key);
+    aks = value & 0x03;
+
+    return aks;
+}
+
+uint8_t
+AT42QT1070::setAKSGroup(uint8_t key, uint8_t group)
+{
+    uint8_t value;
+
+    if (key > 6) {
+        throw std::invalid_argument("Only keys 0-6 are allowed");
+    }
+
+    if (group > 3) {
+        throw std::invalid_argument("Only groups 0-3 are allowed");
+    }
+
+    value = readByte(REG_AVE0 + key);
+    value = value & 0xFC;
+    value = value | group;
+
+    writeByte(REG_AVE0 + key, value);
+
+    return getAKSGroup(key);
+}
+
 bool
 AT42QT1070::reset()
 {

src/at42qt1070/at42qt1070.h

@@ -189,6 +189,14 @@ class AT42QT1070
      */
     uint16_t readWord(uint8_t reg);
 
+
+    /**
+     * Read the Chip ID register on the sensor
+     *
+     * @return the value of the Chip ID register
+     */
+    uint8_t readChipID(void);
+
     /**
      * Read the current touch status and detection state
      *
@@ -196,6 +204,57 @@ class AT42QT1070
      */
     void updateState();
 
+
+    /**
+     * Read the current low-power mode setting
+     *
+     * @return return low-power mode setting from sensor
+     */
+    uint8_t getLPMode(void);
+
+    /**
+     * Change the low-pomer mode setting on the sensor
+     *
+     * @param mode desired new mode
+     * @return new setting on sensor
+     */
+    uint8_t setLPMode(uint8_t mode);
+
+
+    /**
+     * Read the current averaging factor setting for a key
+     *
+     * @param key the key being read
+     * @return the averaging factor
+     */
+    uint8_t getAVE(uint8_t key);
+
+    /**
+     * Change the averaging factor setting for a key
+     *
+     * @param key the key being changed
+     * @param ave the new averaging factor
+     * @return the new averaging factor as read from the device
+     */
+    uint8_t setAVE(uint8_t key, uint8_t ave);
+
+    /**
+     * Read the AKS group a key is part of
+     *
+     * @param key the key (0-6) being queried
+     * @return AKS group the key is part of
+     */
+    uint8_t getAKSGroup(uint8_t key);
+
+    /**
+     * Change the AKS group that a key is part of
+     *
+     * @param key the key (0-6) being changed
+     * @param group the new group for the key
+     * @return return the new value on the sensor
+     */
+    uint8_t setAKSGroup(uint8_t key, uint8_t group);
+
     /**
      * return the overflow indicator
      *