1 files changed, 19 insertions, 2 deletions
diff --git a/src/drivers/Cst816s.cpp b/src/drivers/Cst816s.cpp
index 1ff163b0..5feb17b0 100644
--- a/src/drivers/Cst816s.cpp
+++ b/src/drivers/Cst816s.cpp
@@ -18,7 +18,7 @@ using namespace Pinetime::Drivers;
 Cst816S::Cst816S(TwiMaster& twiMaster, uint8_t twiAddress) : twiMaster {twiMaster}, twiAddress {twiAddress} {
 }
 
-void Cst816S::Init() {
+bool Cst816S::Init() {
   nrf_gpio_cfg_output(PinMap::Cst816sReset);
   nrf_gpio_pin_set(PinMap::Cst816sReset);
   vTaskDelay(50);
@@ -51,6 +51,22 @@ void Cst816S::Init() {
   */
   static constexpr uint8_t irqCtl = 0b01110000;
   twiMaster.Write(twiAddress, 0xFA, &irqCtl, 1);
+
+  // There's mixed information about which register contains which information
+  if (twiMaster.Read(twiAddress, 0xA7, &chipId, 1) == TwiMaster::ErrorCodes::TransactionFailed) {
+    chipId = 0xFF;
+    return false;
+  }
+  if (twiMaster.Read(twiAddress, 0xA8, &vendorId, 1) == TwiMaster::ErrorCodes::TransactionFailed) {
+    vendorId = 0xFF;
+    return false;
+  }
+  if (twiMaster.Read(twiAddress, 0xA9, &fwVersion, 1) == TwiMaster::ErrorCodes::TransactionFailed) {
+    fwVersion = 0xFF;
+    return false;
+  }
+
+  return chipId == 0xb4 && vendorId == 0 && fwVersion == 1;
 }
 
 Cst816S::TouchInfos Cst816S::GetTouchInfo() {
@@ -62,7 +78,8 @@ Cst816S::TouchInfos Cst816S::GetTouchInfo() {
     return info;
   }
 
-  auto nbTouchPoints = touchData[2] & 0x0f;
+  // This can only be 0 or 1
+  auto nbTouchPoints = touchData[touchPointNumIndex] & 0x0f;
 
   auto xHigh = touchData[touchXHighIndex] & 0x0f;
   auto xLow = touchData[touchXLowIndex];