samples: i2s_codec: Refine sample for samll RAM platforms

- Configure BLOCK count by using kconfig option
'EXTRA_BLOCKS' instad of fixed value. This allows user to
customize the RAM usage based on their platform.
- Keep the PCM data in flash to avoid large RAM usage.
- Refine the sample to get the SAMPLE_BIT_WIDTH
and BYTES_PER_SAMPLE from Kconfig options.

Signed-off-by: Zhaoxiang Jin <[email protected]>

Author: ZhaoxiangJin

samples/drivers/i2s/i2s_codec/Kconfig

@@ -25,6 +25,24 @@ config USE_CODEC_CLOCK
 	  to generate those. If not selected, the I2S peripheral will generate
 	  them and the codec will be expected to consume them.
 
+config EXTRA_BLOCKS
+	int "Extra block size"
+	default 32
+	help
+	  Extra blocks for storing PCM sample.
+
+config SAMPLE_WIDTH
+	int "Sample bit width"
+	default 16
+	help
+	  PCM sample bit width.
+
+config BYTES_PER_SAMPLE
+	int "Bytes per sample"
+	default 2
+	help
+	  Number of bytes per PCM sample.
+
 config USE_DMIC
 	bool "Use DMIC as an audio input"
 

samples/drivers/i2s/i2s_codec/src/main.c

@@ -19,8 +19,8 @@
 #define I2S_CODEC_TX DT_ALIAS(i2s_codec_tx)
 
 #define SAMPLE_FREQUENCY CONFIG_SAMPLE_FREQ
-#define SAMPLE_BIT_WIDTH (16U)
-#define BYTES_PER_SAMPLE sizeof(int16_t)
+#define SAMPLE_BIT_WIDTH CONFIG_SAMPLE_WIDTH
+#define BYTES_PER_SAMPLE CONFIG_BYTES_PER_SAMPLE
 #if CONFIG_USE_DMIC
 #define NUMBER_OF_CHANNELS CONFIG_DMIC_CHANNELS
 #else
@@ -32,7 +32,7 @@
 #define TIMEOUT           (2000U)
 
 #define BLOCK_SIZE  (BYTES_PER_SAMPLE * SAMPLES_PER_BLOCK)
-#define BLOCK_COUNT (INITIAL_BLOCKS + 32)
+#define BLOCK_COUNT (INITIAL_BLOCKS + CONFIG_EXTRA_BLOCKS)
 
 K_MEM_SLAB_DEFINE_IN_SECT_STATIC(mem_slab, __nocache, BLOCK_SIZE, BLOCK_COUNT, 4);
 

samples/drivers/i2s/i2s_codec/src/sine.h

@@ -4,19 +4,16 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
- #ifndef SINE_H_
- #define SINE_H_
+#ifndef SINE_H_
+#define SINE_H_
 
-#if CONFIG_NOCACHE_MEMORY
-#define __NOCACHE	__attribute__((__section__(".nocache")))
-#elif defined(CONFIG_DT_DEFINED_NOCACHE)
-#define __NOCACHE	__attribute__((__section__(CONFIG_DT_DEFINED_NOCACHE_NAME)))
-#else /* CONFIG_NOCACHE_MEMORY */
-#define __NOCACHE
-#endif /* CONFIG_NOCACHE_MEMORY */
-
-unsigned char __16kHz16bit_stereo_sine_pcm[] __NOCACHE;
-unsigned char __16kHz16bit_stereo_sine_pcm[] = {
+/*
+ * Keep the PCM data in flash to avoid large RAM usage.
+ * If a platform requires DMA-readable RAM buffers, copy
+ * chunks of this table into a small nocache TX buffer
+ * at runtime instead of keeping the entire table in RAM.
+ */
+static const unsigned char __16kHz16bit_stereo_sine_pcm[] = {
 	0x00, 0x00, 0x00, 0x00, 0x08, 0x0b, 0x08, 0x0b, 0xbb, 0x15, 0xbb, 0x15, 0xc9, 0x1f, 0xc9,
 	0x1f, 0xe4, 0x28, 0xe4, 0x28, 0xc8, 0x30, 0xc8, 0x30, 0x38, 0x37, 0x38, 0x37, 0x03, 0x3c,
 	0x03, 0x3c, 0x04, 0x3f, 0x04, 0x3f, 0x25, 0x40, 0x25, 0x40, 0x5d, 0x3f, 0x5d, 0x3f, 0xb1,
@@ -444,6 +441,6 @@ unsigned char __16kHz16bit_stereo_sine_pcm[] = {
 	0xa3, 0xc0, 0xa3, 0xc0, 0xdb, 0xbf, 0xdb, 0xbf, 0xfc, 0xc0, 0xfc, 0xc0, 0xfd, 0xc3, 0xfd,
 	0xc3, 0xc8, 0xc8, 0xc8, 0xc8, 0x38, 0xcf, 0x38, 0xcf, 0x1c, 0xd7, 0x1c, 0xd7, 0x37, 0xe0,
 	0x37, 0xe0, 0x45, 0xea, 0x45, 0xea, 0xf8, 0xf4, 0xf8, 0xf4};
-const unsigned int __16kHz16bit_stereo_sine_pcm_len = sizeof(__16kHz16bit_stereo_sine_pcm);
+static const unsigned int __16kHz16bit_stereo_sine_pcm_len = ARRAY_SIZE(__16kHz16bit_stereo_sine_pcm);
 
 #endif /* SINE_H_ */