Simplify bias

grc/PicoSDR-WBFM.grc

@@ -40,6 +40,7 @@ blocks:
     const_points: '[-1-1j, -1+1j, 1+1j, 1-1j]'
     dims: '1'
     normalization: digital.constellation.AMPLITUDE_NORMALIZATION
+    npwr: '1.0'
     precision: '8'
     rot_sym: '4'
     soft_dec_lut: None
@@ -77,7 +78,7 @@ blocks:
     bus_sink: false
     bus_source: false
     bus_structure: null
-    coordinate: [704, 296.0]
+    coordinate: [704, 312.0]
     rotation: 0
     state: true
 - name: analog_wfm_rcv_pll_0
@@ -140,11 +141,12 @@ blocks:
     alias: ''
     comment: ''
     en_uvec: 'True'
+    log_level: info
   states:
     bus_sink: false
     bus_source: false
     bus_structure: null
-    coordinate: [1000, 32.0]
+    coordinate: [992, 8.0]
     rotation: 0
     state: true
 - name: blocks_probe_rate_0
@@ -157,6 +159,7 @@ blocks:
     maxoutbuf: '0'
     minoutbuf: '0'
     mintime: '2500'
+    name: ''
     type: complex
     vlen: '1'
   states:
@@ -179,6 +182,30 @@ blocks:
     coordinate: [440, 8.0]
     rotation: 0
     state: true
+- name: low_pass_filter_0
+  id: low_pass_filter
+  parameters:
+    affinity: ''
+    alias: ''
+    beta: '6.76'
+    comment: ''
+    cutoff_freq: samp_rate / 8
+    decim: '4'
+    gain: '1'
+    interp: '1'
+    maxoutbuf: '0'
+    minoutbuf: '0'
+    samp_rate: samp_rate
+    type: fir_filter_fff
+    width: samp_rate / 8
+    win: window.WIN_HAMMING
+  states:
+    bus_sink: false
+    bus_source: false
+    bus_structure: null
+    coordinate: [992, 284.0]
+    rotation: 0
+    state: enabled
 - name: network_tcp_source_0
   id: network_tcp_source
   parameters:
@@ -293,7 +320,7 @@ blocks:
     bus_sink: false
     bus_source: false
     bus_structure: null
-    coordinate: [704, 192.0]
+    coordinate: [704, 208.0]
     rotation: 0
     state: true
 - name: qtgui_time_sink_x_0_0
@@ -351,8 +378,8 @@ blocks:
     marker9: '-1'
     name: '"FM Demodulation"'
     nconnections: '1'
-    size: int(samp_rate // 30)
+    size: '512'
-    srate: samp_rate
+    srate: samp_rate // (2 ** 3)
     stemplot: 'False'
     style1: '1'
     style10: '1'
@@ -390,7 +417,7 @@ blocks:
     bus_sink: false
     bus_source: false
     bus_structure: null
-    coordinate: [992, 272.0]
+    coordinate: [1192, 312.0]
     rotation: 0
     state: true
 - name: qtgui_waterfall_sink_x_0_0
@@ -451,7 +478,7 @@ blocks:
     bus_sink: false
     bus_source: false
     bus_structure: null
-    coordinate: [704, 88.0]
+    coordinate: [704, 104.0]
     rotation: 0
     state: true
 - name: qtgui_waterfall_sink_x_0_0_0
@@ -573,12 +600,12 @@ blocks:
     bus_sink: false
     bus_source: false
     bus_structure: null
-    coordinate: [992, 168.0]
+    coordinate: [992, 184.0]
     rotation: 0
     state: true
 
 connections:
-- [analog_quadrature_demod_cf_0, '0', qtgui_time_sink_x_0_0, '0']
+- [analog_quadrature_demod_cf_0, '0', low_pass_filter_0, '0']
 - [analog_quadrature_demod_cf_0, '0', qtgui_waterfall_sink_x_0_0_0_0, '0']
 - [analog_wfm_rcv_pll_0, '0', audio_sink_0, '0']
 - [analog_wfm_rcv_pll_0, '0', qtgui_waterfall_sink_x_0_0_0, '0']
@@ -590,8 +617,9 @@ connections:
 - [blocks_interleaved_short_to_complex_0, '0', qtgui_time_sink_x_0, '0']
 - [blocks_interleaved_short_to_complex_0, '0', qtgui_waterfall_sink_x_0_0, '0']
 - [blocks_probe_rate_0, rate, blocks_message_debug_0, print]
+- [low_pass_filter_0, '0', qtgui_time_sink_x_0_0, '0']
 - [network_tcp_source_0, '0', blocks_interleaved_short_to_complex_0, '0']
 
 metadata:
   file_format: 1
-  grc_version: 3.10.6.0
+  grc_version: 3.10.9.2

src/main.c

@@ -45,7 +45,6 @@
 #define DECIMATION_BITS 3
 #define LPF_ORDER 4
 #define AGC_DECAY_BITS 20
-#define BIAS_STRENGTH 0
 #define LO_DITHER 0
 #endif
 
@@ -57,7 +56,6 @@
 #define DECIMATION_BITS 6
 #define LPF_ORDER 4
 #define AGC_DECAY_BITS 16
-#define BIAS_STRENGTH 3
 #define LO_DITHER 1
 #endif
 
@@ -67,7 +65,6 @@
 
 static_assert(RX_SLEEP_US > 0, "RX_SLEEP_US must be positive");
 static_assert(LPF_ORDER <= 4, "LPF_ORDER must be 0-4");
-static_assert(BIAS_STRENGTH >= 0 && BIAS_STRENGTH <= 9, "BIAS_STRENGTH must be 0-9");
 
 #define XOR_ADDR 0x1000
 #define LO_COS_ACCUMULATOR (&pio1->sm[2].pinctrl)
@@ -129,33 +126,12 @@ static void bias_init(int in_pin, int out_pin)
 
 	const uint16_t insn[] = {
 		pio_encode_mov_not(pio_pins, pio_pins) | pio_encode_sideset(1, 1),
+		pio_encode_set(pio_x, 4) | pio_encode_sideset(1, 0) | pio_encode_delay(15),
+		pio_encode_jmp_x_dec(2) | pio_encode_sideset(1, 0) | pio_encode_delay(15),
+
 		pio_encode_mov_not(pio_pins, pio_pins) | pio_encode_sideset(1, 1),
-
+		pio_encode_set(pio_x, 4) | pio_encode_sideset(1, 0) | pio_encode_delay(15),
-		pio_encode_nop() | pio_encode_sideset(1, 0) | pio_encode_delay(0), /* 1 */
+		pio_encode_jmp_x_dec(5) | pio_encode_sideset(1, 0) | pio_encode_delay(15),
-		pio_encode_nop() | pio_encode_sideset(1, 0) | pio_encode_delay(0), /* 2 */
-		pio_encode_nop() | pio_encode_sideset(1, 0) | pio_encode_delay(1), /* 4 */
-		pio_encode_nop() | pio_encode_sideset(1, 0) | pio_encode_delay(3), /* 8 */
-
-		pio_encode_nop() | pio_encode_sideset(1, 0) | pio_encode_delay(7),  /* 16 */
-		pio_encode_nop() | pio_encode_sideset(1, 0) | pio_encode_delay(15), /* 32 */
-		pio_encode_nop() | pio_encode_sideset(1, 0) | pio_encode_delay(15), /* 48 */
-		pio_encode_nop() | pio_encode_sideset(1, 0) | pio_encode_delay(15), /* 64 */
-
-		pio_encode_nop() | pio_encode_sideset(1, 0) | pio_encode_delay(15),
-		pio_encode_nop() | pio_encode_sideset(1, 0) | pio_encode_delay(15),
-		pio_encode_nop() | pio_encode_sideset(1, 0) | pio_encode_delay(15),
-		pio_encode_nop() | pio_encode_sideset(1, 0) | pio_encode_delay(15),
-
-		pio_encode_nop() | pio_encode_sideset(1, 0) | pio_encode_delay(15),
-		pio_encode_nop() | pio_encode_sideset(1, 0) | pio_encode_delay(15),
-		pio_encode_nop() | pio_encode_sideset(1, 0) | pio_encode_delay(15),
-		pio_encode_nop() | pio_encode_sideset(1, 0) | pio_encode_delay(15),
-
-		pio_encode_nop() | pio_encode_sideset(1, 0) | pio_encode_delay(15),
-		pio_encode_nop() | pio_encode_sideset(1, 0) | pio_encode_delay(15),
-
-		pio_encode_set(pio_x, 7) | pio_encode_sideset(1, 0) | pio_encode_delay(15),
-		pio_encode_jmp_x_dec(21) | pio_encode_sideset(1, 0) | pio_encode_delay(15),
 	};
 
 	pio_program_t prog = {
@@ -178,8 +154,7 @@ static void bias_init(int in_pin, int out_pin)
 	sm_config_set_out_pins(&pc, out_pin, 1);
 	sm_config_set_set_pins(&pc, out_pin, 1);
 
-	int nops[10] = { 20, 12, 8, 6, 5, 4, 3, 2, 1, 0 };
+	sm_config_set_wrap(&pc, prog.origin, prog.origin + prog.length - 1);
-	sm_config_set_wrap(&pc, prog.origin, prog.origin + 1 + nops[BIAS_STRENGTH]);
 
 	sm_config_set_clkdiv_int_frac(&pc, 1, 0);
 	pio_sm_init(pio1, 0, prog.origin, &pc);