Merge pull request #16 from chirp/bug/use-high-freq-oscillator

Fix: Use high freq oscillator

Author: ideoforms

CHANGELOG.md

@@ -2,6 +2,9 @@
 
 Recent changes to the [Chirp Arduino SDK](https://developers.chirp.io/docs).
 
+## v3.3.1 (beta)
+ - Use high frequency oscillator in Nano 33 Sense examples
+
 ## v3.3.0 (09/08/2019)
 
  - Added support for cortex-m4 (Nano 33 Sense)

README.md

@@ -1,6 +1,6 @@
 # Chirp for Arduino
 
-*Version 3.3.0, August 2019*
+*Version 3.3.1, August 2019*
 
 ## Overview
 
@@ -10,7 +10,7 @@ Chirp is a library enabling Arduino-based devices to send and receive data using
  * A digital I2S MEMS microphone (if your board does not contain a microphone)
  * A digital I2S amplifier and compatible speaker
 
-For receiving data, you will need a digital MEMS microphone. Some boards (for example, the Nano 33 Sense and Microsoft MXChip) already include a MEMS mic so you are good to go. For others, you will need an external mic such as the [SPH0645](https://www.adafruit.com/product/3421) or [ICS-43434](https://www.mouser.co.uk/ProductDetail/TDK-InvenSense/ICS-43434?qs=u4fy%2FsgLU9PAgmWRI7%252BqXA%3D%3D). 
+For receiving data, you will need a digital MEMS microphone. Some boards (for example, the Nano 33 Sense and Microsoft MXChip) already include a MEMS mic so you are good to go. For others, you will need an external mic such as the [SPH0645](https://www.adafruit.com/product/3421) or [ICS-43434](https://www.mouser.co.uk/ProductDetail/TDK-InvenSense/ICS-43434?qs=u4fy%2FsgLU9PAgmWRI7%252BqXA%3D%3D).
 
 For sending data, we recommend using a digital I2S audio output such as the [UDA1334A](https://www.adafruit.com/product/3678) or [MAX98357A](https://www.adafruit.com/product/3006), connected to a compatible speaker.
 

examples/Nano33SenseReceive/Nano33SenseReceive.ino

@@ -52,6 +52,11 @@ void setup()
   Serial.begin(115200);
   while (!Serial);
 
+  // Enable high frequency oscillator
+  NRF_CLOCK->EVENTS_HFCLKSTARTED = 0;
+  NRF_CLOCK->TASKS_HFCLKSTART    = 1;
+  while (NRF_CLOCK->EVENTS_HFCLKSTARTED == 0);
+
   setupChirp();
 
   PDM.onReceive(onPDMdata);
@@ -144,7 +149,7 @@ void setupChirp(void)
   // A fixed frequency correction coefficient is needed to correct a clock
   // mismatch between the 16000Hz requested sample rate and the Nano's actual
   // audio sample rate.
-  err = chirp_connect_set_frequency_correction(chirp, 1.0096);
+  err = chirp_connect_set_frequency_correction(chirp, 1.00812);
   chirpErrorHandler(err);
 
   err = chirp_connect_start(chirp);

examples/Nano33SenseSend/Nano33SenseSend.ino

@@ -27,7 +27,7 @@
 #include "chirp_connect.h"
 #include "credentials.h"
 
-#define VOLUME                 0.3  // Between 0 and 1
+#define VOLUME                 0.1  // Between 0 and 1
 #define BUFFER_SIZE            256
 #define OUTPUT_SAMPLE_RATE     16667
 
@@ -57,6 +57,11 @@ void setup()
   Serial.begin(115200);
   while(!Serial);  // Wait for Serial monitor before continuing
 
+  // Enable high frequency oscillator
+  NRF_CLOCK->EVENTS_HFCLKSTARTED = 0;
+  NRF_CLOCK->TASKS_HFCLKSTART    = 1;
+  while (NRF_CLOCK->EVENTS_HFCLKSTARTED == 0);
+
   setupChirp();
   sendChirp();
 

library.properties

@@ -1,5 +1,5 @@
 name=ChirpSDK
-version=3.3.0
+version=3.3.1
 author=Asio Ltd <developers@chirp.io>
 maintainer=Joe Todd <joe@chirp.io>
 sentence=Chirp SDK