Reset GPIO pin state on Pisound destruction

Fixes #233.

CHANGELOG.md

@@ -15,6 +15,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - A bug in the config file reader (unterminated string) could cause the last entry in the file to be read as a corrupted value if the file ended without a newline.
 - Some FTP commands could work without being logged in.
+- Some DAC accessories which make use of a hardware "mute" pin (e.g. Adafruit I²S Audio Bonnet) could be held in a muted state due to a conflict with the Blokas Pisound driver's probing routine (issue #233). The driver now resets these GPIO pins to the initial power-on state, which should fix this issue. Thanks to @htamas2 for the report!
 
 ## [0.11.0] - 2021-12-12
 

include/pisound.h

@@ -34,6 +34,7 @@ class CPisound
 	using TMIDIReceiveHandler = void (*)(const u8* pData, size_t nSize);
 
 	CPisound(CSPIMaster* pSPIMaster, CGPIOManager* pGPIOManager, unsigned nSamplerate);
+	~CPisound();
 
 	bool Initialize();
 	void RegisterMIDIReceiveHandler(TMIDIReceiveHandler pHandler) { m_pReceiveHandler = pHandler; }

src/pisound.cpp

@@ -71,6 +71,17 @@ CPisound::CPisound(CSPIMaster* pSPIMaster, CGPIOManager* pGPIOManager, unsigned
 {
 }
 
+CPisound::~CPisound()
+{
+	// Reset GPIO pins to default boot-up state
+	m_SPIReset.SetMode(TGPIOMode::GPIOModeInputPullDown);
+	m_DataAvailable.SetMode(TGPIOMode::GPIOModeInputPullDown);
+	m_ADCReset.SetMode(TGPIOMode::GPIOModeInputPullDown);
+	m_OversamplingRatio0.SetMode(TGPIOMode::GPIOModeInputPullDown);
+	m_OversamplingRatio1.SetMode(TGPIOMode::GPIOModeInputPullDown);
+	m_OversamplingRatio2.SetMode(TGPIOMode::GPIOModeInputPullDown);
+}
+
 bool CPisound::Initialize()
 {
 	assert(m_pSPIMaster != nullptr);