diff --git a/libctru/include/3ds.h b/libctru/include/3ds.h
index 9aeb842..141c6cc 100644
--- a/libctru/include/3ds.h
+++ b/libctru/include/3ds.h
@@ -79,6 +79,7 @@ extern "C" {
 #include <3ds/services/loader.h>
 #include <3ds/services/y2r.h>
 #include <3ds/services/mcuhwc.h>
+#include <3ds/services/cdcchk.h>
 
 #include <3ds/gpu/gx.h>
 #include <3ds/gpu/gpu.h>
diff --git a/libctru/include/3ds/services/cdcchk.h b/libctru/include/3ds/services/cdcchk.h
new file mode 100644
index 0000000..8917f89
--- /dev/null
+++ b/libctru/include/3ds/services/cdcchk.h
@@ -0,0 +1,90 @@
+/**
+ * @file cdcchk.h
+ * @brief CODEC Hardware Check service.
+ */
+#pragma once
+
+#include <3ds/types.h>
+
+/// I2S line enumeration
+typedef enum {
+    CODEC_I2S_LINE_1,     ///< Primary I2S line, used by DSP/Mic (configurable)/GBA sound controller.
+    CODEC_I2S_LINE_2,     ///< Secondary I2S line, used by CSND hardware.
+} CodecI2sLine;
+
+/// Initializes CDCCHK.
+Result cdcChkInit(void);
+
+/// Exits CDCCHK.
+void cdcChkExit(void);
+
+/**
+ * @brief Gets a pointer to the current cdc:CHK session handle.
+ * @return A pointer to the current cdc:CHK session handle.
+ */
+Handle *cdcChkGetSessionHandle(void);
+
+/**
+ * @brief Reads multiple registers from the CODEC, using the old
+ * SPI hardware interface and a 4MHz baudrate.
+ * @param pageId CODEC Page ID.
+ * @param initialRegAddr Address of the CODEC register to start with.
+ * @param[out] outData Where to write the read data to.
+ * @param size Number of registers to read (bytes to read, max. 64).
+ */
+Result CDCCHK_ReadRegisters1(u8 pageId, u8 initialRegAddr, void *outData, size_t size);
+
+/**
+ * @brief Reads multiple registers from the CODEC, using the new
+ * SPI hardware interface and a 16MHz baudrate.
+ * @param pageId CODEC Page ID.
+ * @param initialRegAddr Address of the CODEC register to start with.
+ * @param[out] outData Where to read the data to.
+ * @param size Number of registers to read (bytes to read, max. 64).
+ */
+Result CDCCHK_ReadRegisters2(u8 pageId, u8 initialRegAddr, void *outData, size_t size);
+
+/**
+ * @brief Writes multiple registers to the CODEC, using the old
+ * SPI hardware interface and a 4MHz baudrate.
+ * @param pageId CODEC Page ID.
+ * @param initialRegAddr Address of the CODEC register to start with.
+ * @param data Where to read the data to write from.
+ * @param size Number of registers to write (bytes to read, max. 64).
+ */
+Result CDCCHK_WriteRegisters1(u8 pageId, u8 initialRegAddr, const void *data, size_t size);
+
+/**
+ * @brief Writes multiple registers to the CODEC, using the new
+ * SPI hardware interface and a 16MHz baudrate.
+ * @param pageId CODEC Page ID.
+ * @param initialRegAddr Address of the CODEC register to start with.
+ * @param data Where to read the data to write from.
+ * @param size Number of registers to write (bytes to read, max. 64).
+ */
+Result CDCCHK_WriteRegisters2(u8 pageId, u8 initialRegAddr, const void *data, size_t size);
+
+/**
+ * @brief Reads a single register from the NTR PMIC.
+ * @param[out] outData Where to read the data to (1 byte).
+ * @param regAddr Register address.
+ * @note The NTR PMIC is emulated by the CODEC hardware and sends
+ * IRQs to the MCU when relevant.
+ */
+Result CDCCHK_ReadNtrPmicRegister(u8 *outData, u8 regAddr);
+
+/**
+ * @brief Writes a single register from the NTR PMIC.
+ * @param regAddr Register address.
+ * @param data Data to write (1 byte).
+ * @note The NTR PMIC is emulated by the CODEC hardware and sends
+ * IRQs to the MCU when relevant.
+ */
+Result CDCCHK_WriteNtrPmicRegister(u8 regAddr, u8 data);
+
+/** 
+ * @brief Sets the DAC volume level for the specified I2S line.
+ * @param i2sLine I2S line to set the volume for.
+ * @param volume Volume level (-128 to 0).
+*/
+Result CDCCHK_SetI2sVolume(CodecI2sLine i2sLine, s8 volume);
diff --git a/libctru/source/services/cdcchk.c b/libctru/source/services/cdcchk.c
new file mode 100644
index 0000000..5491058
--- /dev/null
+++ b/libctru/source/services/cdcchk.c
@@ -0,0 +1,162 @@
+#include <string.h>
+#include <3ds/types.h>
+#include <3ds/result.h>
+#include <3ds/svc.h>
+#include <3ds/srv.h>
+#include <3ds/synchronization.h>
+#include <3ds/ipc.h>
+#include <3ds/services/cdcchk.h>
+
+static Handle cdcChkHandle;
+static int cdcChkRefCount;
+
+Result cdcChkInit(void)
+{
+	if (AtomicPostIncrement(&cdcChkRefCount))
+		return 0;
+
+	Result res = srvGetServiceHandle(&cdcChkHandle, "cdc:CHK");
+	if (R_FAILED(res))
+		AtomicDecrement(&cdcChkRefCount);
+	return res;
+}
+
+void cdcChkExit(void)
+{
+	if (AtomicDecrement(&cdcChkRefCount))
+		return;
+	svcCloseHandle(cdcChkHandle);
+}
+
+Handle *cdcChkGetSessionHandle(void)
+{
+	return &cdcChkHandle;
+}
+
+Result CDCCHK_ReadRegisters1(u8 pageId, u8 initialRegAddr, void *outData, size_t size)
+{
+	Result ret = 0;
+	u32 *cmdbuf = getThreadCommandBuffer();
+	u32 *staticbufs = getThreadStaticBuffers();
+
+	u32 staticbufBackup[2];
+	memcpy(staticbufBackup, staticbufs, 8);
+
+	staticbufs[0] = IPC_Desc_StaticBuffer(size, 0);
+	staticbufs[1] = (u32)outData;
+
+	cmdbuf[0] = IPC_MakeHeader(1, 3, 0); // 0x100C0
+	cmdbuf[1] = pageId;
+	cmdbuf[2] = initialRegAddr;
+	cmdbuf[3] = size;
+
+	ret = svcSendSyncRequest(cdcChkHandle);
+
+	memcpy(staticbufs, staticbufBackup, 8);
+
+	return R_SUCCEEDED(ret) ? cmdbuf[1] : ret;
+}
+
+Result CDCCHK_ReadRegisters2(u8 pageId, u8 initialRegAddr, void *outData, size_t size)
+{
+	Result ret = 0;
+	u32 *cmdbuf = getThreadCommandBuffer();
+	u32 *staticbufs = getThreadStaticBuffers();
+
+	u32 staticbufBackup[2];
+	memcpy(staticbufBackup, staticbufs, 8);
+
+	staticbufs[0] = IPC_Desc_StaticBuffer(size, 0);
+	staticbufs[1] = (u32)outData;
+
+	cmdbuf[0] = IPC_MakeHeader(2, 3, 0); // 0x200C0
+	cmdbuf[1] = pageId;
+	cmdbuf[2] = initialRegAddr;
+	cmdbuf[3] = size;
+
+	ret = svcSendSyncRequest(cdcChkHandle);
+
+	memcpy(staticbufs, staticbufBackup, 8);
+
+	return R_SUCCEEDED(ret) ? cmdbuf[1] : ret;
+}
+
+Result CDCCHK_WriteRegisters1(u8 pageId, u8 initialRegAddr, const void *data, size_t size)
+{
+	Result ret = 0;
+	u32 *cmdbuf = getThreadCommandBuffer();
+
+	cmdbuf[0] = IPC_MakeHeader(3, 3, 2); // 0x300C2
+	cmdbuf[1] = pageId;
+	cmdbuf[2] = initialRegAddr;
+	cmdbuf[3] = size;
+	cmdbuf[4] = IPC_Desc_StaticBuffer(size, 0);
+	cmdbuf[5] = (u32)data;
+
+	ret = svcSendSyncRequest(cdcChkHandle);
+
+	return R_SUCCEEDED(ret) ? cmdbuf[1] : ret;
+}
+
+Result CDCCHK_WriteRegisters2(u8 pageId, u8 initialRegAddr, const void *data, size_t size)
+{
+	Result ret = 0;
+	u32 *cmdbuf = getThreadCommandBuffer();
+
+	cmdbuf[0] = IPC_MakeHeader(4, 3, 2); // 0x400C2
+	cmdbuf[1] = pageId;
+	cmdbuf[2] = initialRegAddr;
+	cmdbuf[3] = size;
+	cmdbuf[4] = IPC_Desc_StaticBuffer(size, 0);
+	cmdbuf[5] = (u32)data;
+
+	ret = svcSendSyncRequest(cdcChkHandle);
+
+	return R_SUCCEEDED(ret) ? cmdbuf[1] : ret;
+}
+
+Result CDCCHK_ReadNtrPmicRegister(u8 *outData, u8 regAddr)
+{
+	Result ret = 0;
+	u32 *cmdbuf = getThreadCommandBuffer();
+
+	cmdbuf[0] = IPC_MakeHeader(5, 1, 0); // 0x50040
+	cmdbuf[1] = regAddr;
+
+	ret = svcSendSyncRequest(cdcChkHandle);
+	if (R_SUCCEEDED(ret))
+	{
+		*outData = (u8)cmdbuf[2];
+		ret = cmdbuf[1];
+	}
+
+	return ret;
+}
+
+Result CDCCHK_WriteNtrPmicRegister(u8 regAddr, u8 data)
+{
+	Result ret = 0;
+	u32 *cmdbuf = getThreadCommandBuffer();
+
+	cmdbuf[0] = IPC_MakeHeader(6, 2, 0); // 0x60080
+	cmdbuf[1] = regAddr;
+	cmdbuf[2] = data;
+
+	ret = svcSendSyncRequest(cdcChkHandle);
+
+	return R_SUCCEEDED(ret) ? cmdbuf[1] : ret;
+}
+
+Result CDCCHK_SetI2sVolume(CodecI2sLine i2sLine, s8 volume)
+{
+	Result ret = 0;
+	u32 *cmdbuf = getThreadCommandBuffer();
+
+	cmdbuf[0] = IPC_MakeHeader(7, 2, 0); // 0x70080
+	cmdbuf[1] = (u32)i2sLine;
+	cmdbuf[2] = volume;
+
+	ret = svcSendSyncRequest(cdcChkHandle);
+
+	return R_SUCCEEDED(ret) ? cmdbuf[1] : ret;
+}