pdm: Try switch to 2 stage CIC

Still seeing odd spikes on output

3 files changed, 14 insertions, 12 deletions

diff --git a/bindings/galearn_pdm.cpp b/bindings/galearn_pdm.cpp
index 6952a7c..13c3d4c 100644
--- a/bindings/galearn_pdm.cpp
+++ b/bindings/galearn_pdm.cpp
@@ -1,13 +1,14 @@
 #include <pybind11/numpy.h>
 #include <pybind11/pybind11.h>
 
-int pdm2pcm_cic3(const uint8_t *pdm, int pdm_length, int16_t *pcm,
-		 int pcm_length);
+int pdm2pcm_cic3(const uint8_t *pdm, int64_t pdm_length,
+        int16_t *pcm, int32_t pcm_length,
+        uint8_t hpf_alpha, uint8_t scale_shift);
 
 namespace py = pybind11;
 
 int
-process(py::array_t<uint8_t> arr1, py::array_t<int16_t> arr2)
+process(py::array_t<uint8_t> arr1, py::array_t<int16_t> arr2, int hpf_alpha, int scale_shift)
 {
 	// Check shapes or sizes if needed
 	auto buf1 = arr1.request();
@@ -25,7 +26,7 @@ process(py::array_t<uint8_t> arr1, py::array_t<int16_t> arr2)
 	uint8_t *in = static_cast<uint8_t *>(buf1.ptr);
 	int16_t *out = static_cast<int16_t *>(buf2.ptr);
 
-	int samples = pdm2pcm_cic3(in, arr1.size(), out, arr2.size());
+	int samples = pdm2pcm_cic3(in, arr1.size(), out, arr2.size(), hpf_alpha, scale_shift);
 
 	return samples;
 }
diff --git a/bindings/sim_cic3_pdm.cc b/bindings/sim_cic3_pdm.cc
index cb612f8..982581f 100644
--- a/bindings/sim_cic3_pdm.cc
+++ b/bindings/sim_cic3_pdm.cc
@@ -6,7 +6,7 @@
 #include "verilated.h"
 
 int
-pdm2pcm_cic3(const uint8_t *pdm, int pdm_length, int16_t *pcm, int pcm_length)
+pdm2pcm_cic3(const uint8_t *pdm, int64_t pdm_length, int16_t *pcm, int32_t pcm_length, uint8_t hpf_alpha, uint8_t scale_shift)
 {
 
 	// FIXME: verify that output buffer is large enough
@@ -15,7 +15,8 @@ pdm2pcm_cic3(const uint8_t *pdm, int pdm_length, int16_t *pcm, int pcm_length)
 
 	Vcic3_pdm *top = new Vcic3_pdm{cp};
 
-    top->hpf_alpha = 240;
+    top->hpf_alpha = hpf_alpha;
+    top->scale_shift = scale_shift;
 
 	// Start clock off
 	top->clk = 0;
diff --git a/bindings/test_galearn_pdm.py b/bindings/test_galearn_pdm.py
index 5256a46..3a19762 100644
--- a/bindings/test_galearn_pdm.py
+++ b/bindings/test_galearn_pdm.py
@@ -76,8 +76,8 @@ def test_sine_simple(frequency):
     out = numpy.zeros(shape=len(pdm_input)//DECIMATION, dtype=numpy.int16)
 
     # Process using filter
-    n_samples = galearn_pdm.process(pdm_input, out)
-    out = out / 1024 # XXX: where does this magical come from?
+    n_samples = galearn_pdm.process(pdm_input, out, 255, 1)
+    out = out / (2**15)
 
     # Compensate for delay through filter
     delay = find_forward_shift(pcm_input, out)
@@ -126,19 +126,19 @@ def test_dc():
     function = sys._getframe().f_code.co_name # looks up function name
     test_name = f'{function}' 
     sr = SAMPLERATE_DEFAULT
-    test_duration = 0.10
+    test_duration = 0.0013
 
     # Generate test data
     frequency = 1000
     pcm_input = generate_test_tone(duration_sec=test_duration,
         freqs=[frequency], noise_level=0.0, sample_rate=sr, amplitude=0.01,
-    ) + 0.20 # DC
+    ) + 0.10 # DC
     pdm_input = convert(pcm_input)
     out = numpy.zeros(shape=len(pdm_input)//DECIMATION, dtype=numpy.int16)
 
     # Process using filter
-    n_samples = galearn_pdm.process(pdm_input, out)
-    out = out / 1024 # XXX: where does this magical come from?
+    n_samples = galearn_pdm.process(pdm_input, out, 200, 1)
+    out = out / (2**15) # XXX: where does this magical come from?
 
     # Compensate for delay through filter
     delay = find_forward_shift(pcm_input, out)