How to change the sample-rate and bit-depth of the UAC sample ?

[aa889788]

I would like to convert the UAC as my sdr device IF output to PC, so higher sample-rate and bit-depth would be better, how to change the microphone param of the UAC sample?
我想用UAC当作SDR设备的中频输出，所以想把UAC例子里的麦克风采样率和位深调高一点，不知道要怎么修改？

[WangXuan95]

你好。首先是描述符的修改，在 usb_audio_top.v 第200多行修改 usbfs_core_top 的parameter，具体参考 UAC specification https://www.usb.org/document-library/audio-device-class-spec-basic-audio-devices-v10-and-adopters-agreement : USB Audio Class (UAC) 1.0 Specification 。UAC可能会有最高频率限制，注意一下。

然后修改 usb_audio_top.v 54~67 行，让生成的 audio_en 脉冲信号的频率等于你想要的频率，让生产者的速度和消费者的速度匹配。

[aa889788]

你好。首先是描述符的修改，在 usb_audio_top.v 第200多行修改 usbfs_core_top 的parameter，具体参考 UAC specification https://www.usb.org/document-library/audio-device-class-spec-basic-audio-devices-v10-and-adopters-agreement : USB Audio Class (UAC) 1.0 Specification 。UAC可能会有最高频率限制，注意一下。

然后修改 usb_audio_top.v 54~67 行，让生成的 audio_en 脉冲信号的频率等于你想要的频率，让生产者的速度和消费者的速度匹配。

我之前将麦克风的位深改为24bit，采样率不变，烧录后麦克风通道看不到数据

diff --git a/RTL/usb_class/usb_audio_top.v b/RTL/usb_class/usb_audio_top.v
index 63be7b8..1061264 100644
--- a/RTL/usb_class/usb_audio_top.v
+++ b/RTL/usb_class/usb_audio_top.v
@@ -23,8 +23,8 @@ module usb_audio_top #(
     output reg         audio_en,      // a 48kHz pulse, that is, audio_en=1 for 1 cycle every 1250 cycles. Note that 60MHz/48kHz=1250, where 60MHz is clk frequency.
     output reg  [15:0] audio_lo,      // left-channel  output: 16-bit signed integer, which will be valid when audio_en=1
     output reg  [15:0] audio_ro,      // right-channel output: 16-bit signed integer, which will be valid when audio_en=1
-    input  wire [15:0] audio_li,      // left-channel  input : 16-bit signed integer, which will be sampled when audio_en=1
-    input  wire [15:0] audio_ri,      // right-channel input : 16-bit signed integer, which will be sampled when audio_en=1
+    input  wire [23:0] audio_li,      // left-channel  input : 16-bit signed integer, which will be sampled when audio_en=1
+    input  wire [23:0] audio_ri,      // right-channel input : 16-bit signed integer, which will be sampled when audio_en=1
     // debug output info, only for USB developers, can be ignored for normally use. Please set DEBUG="TRUE" to enable these signals
     output wire        debug_en,      // when debug_en=1 pulses, a byte of debug info appears on debug_data
     output wire [ 7:0] debug_data,    // 
@@ -134,10 +134,10 @@ always @ (posedge clk or negedge usb_rstn)
 //-------------------------------------------------------------------------------------------------------------------------------------
 // audio input (device-to-host) : buffer. The goal is to convert the stable 48ksps audio input to the USB-packet-burst data.
 //-------------------------------------------------------------------------------------------------------------------------------------
-reg [31:0] bufi [511:0];             // may automatically synthesize to BRAM
+reg [47:0] bufi [511:0];             // may automatically synthesize to BRAM
 reg [ 9:0] bufi_wptr = 10'h0;
 reg [ 9:0] bufi_rptr = 10'h0;
-reg [31:0] bufi_rd;
+reg [47:0] bufi_rd;
 wire bufi_full_n  = (bufi_wptr != {~bufi_rptr[9], bufi_rptr[8:0]});
 wire bufi_empty_n = (bufi_wptr != bufi_rptr);
 
@@ -161,23 +161,23 @@ always @ (posedge clk)
 //-------------------------------------------------------------------------------------------------------------------------------------
 // audio input (device-to-host) : convert 2-channel-16-bit-PCM to byte stream
 //-------------------------------------------------------------------------------------------------------------------------------------
-reg [ 1:0] i_pcm_cnt = 2'h0;    // count from 0~3
-reg [ 5:0] i_pkt_cnt = 6'h0;    // count from 0~47, since each USB packet carries 48 PCM data (2 channel * 2 byte * 48 = 192 bytes each packet)
+reg [ 2:0] i_pcm_cnt = 3'h0;    // count from 0~5
+reg [ 5:0] i_pkt_cnt = 6'h0;    // count from 0~47, since each USB packet carries 48 PCM data (2 channel * 3 byte * 48 = 192 bytes each packet)
 
 always @ (posedge clk or negedge usb_rstn)
     if (~usb_rstn) begin
         bufi_rptr <= 10'h0;
-        i_pcm_cnt <= 2'h0;
+        i_pcm_cnt <= 3'h0;
         i_pkt_cnt <= 6'h0;
         in_valid <= 1'b0;
     end else begin
         if (sof) begin
-            i_pcm_cnt <= 2'h0;
+            i_pcm_cnt <= 3'h0;
             i_pkt_cnt <= 6'h0;
             in_valid <= 1'b1;
         end else if (in_ready) begin
-            i_pcm_cnt <= i_pcm_cnt + 2'd1;
-            if (i_pcm_cnt == 2'd3) begin
+            i_pcm_cnt <= i_pcm_cnt + 3'd1;
+            if (i_pcm_cnt == 3'd5) begin
                 if (i_pkt_cnt < 6'd47) begin
                     i_pkt_cnt <= i_pkt_cnt + 6'd1;
                     in_valid <= 1'b1;
@@ -229,8 +229,8 @@ usbfs_core_top  #(
         72'h09_04_01_00_00_01_02_00_03,            // interface descriptor
         72'h09_04_01_01_01_01_02_00_03,            // interface descriptor, audio streaming (AS)
         56'h07_24_01_02_01_01_00,                  // AS interface descriptor, link to terminal ID=0x02, interface delay=0x01, PCM format
-        88'h0B_24_02_01_02_02_10_01_80_BB_00,      // AS format type descriptor, 2channel (stereo), 16bit 48000Hz
-        72'h09_05_82_01_C0_00_01_00_00,            // endpoint descriptor, endpoint 0x82, 0xC0=192=48*2*2 bytes per packet, one packet per frame (1frame = 1ms)
+        88'h0B_24_02_01_02_03_18_01_80_BB_00,      // AS format type descriptor, 2channel (stereo), 16bit 48000Hz
+        72'h09_05_82_01_20_01_01_00_00,            // endpoint descriptor, endpoint 0x82, 0xC0=192=48*2*2 bytes per packet, one packet per frame (1frame = 1ms)
         56'h07_25_01_00_00_00_00,                  // audio data endpoint descriptor
         72'h09_04_02_00_00_01_02_00_04,            // interface descriptor
         72'h09_04_02_01_01_01_02_00_04,            // interface descriptor, audio streaming (AS)
@@ -240,7 +240,7 @@ usbfs_core_top  #(
         56'h07_25_01_01_00_00_00,                  // audio data endpoint descriptor
         2704'h0
     } ),
-    .EP82_MAXPKTSIZE    ( 10'hC0           ),    // USB packet length = 192 bytes = 2 channel * 2 byte * 48 PCM datas
+    .EP82_MAXPKTSIZE    ( 10'h120           ),    // USB packet length = 192 bytes = 2 channel * 2 byte * 48 PCM datas
     .EP82_ISOCHRONOUS   ( 1                ),
     .EP01_ISOCHRONOUS   ( 1                ),
     .DEBUG              ( DEBUG            )