Fix onset click

Jenkinsfile

@@ -1,6 +1,6 @@
 // This file relates to internal XMOS infrastructure and should be ignored by external users
 
-@Library('xmos_jenkins_shared_library@v0.49.0') _
+@Library('xmos_jenkins_shared_library@v0.52.0') _
 
 getApproval()
 pipeline {

lib_mic_array/api/mic_array/cpp/PdmRx.hpp

@@ -473,6 +473,34 @@ void mic_array::StandardPdmRxService<CHANNELS_IN, CHANNELS_OUT>::SetPort(port_t
 template <unsigned CHANNELS_IN, unsigned CHANNELS_OUT>
 void mic_array::StandardPdmRxService<CHANNELS_IN, CHANNELS_OUT>::ThreadEntry()
 {
+
+  uint32_t good_frames = 0;
+  while(1){
+    // During boot, the PDM port may read all 0s or all 1s.
+    // Output 0x55 (zero) to the buffer until we get a valid frame.
+    uint32_t data = port_in(this->p_pdm_mics);
+    this->blocks[0][--phase] =  0x55555555;
+
+    if(!phase){
+      this->phase = this->num_phases;
+      uint32_t* ready_block = this->blocks[0];
+      this->blocks[0] = this->blocks[1];
+      this->blocks[1] = ready_block;
+
+      s_chan_out_word(this->c_pdm_blocks.end_a, reinterpret_cast<uint32_t>(ready_block));
+    }
+    if (data == 0x00000000 || data == 0xFFFFFFFF) {
+      good_frames = 0;
+      continue;
+    }
+    good_frames++;
+    if (good_frames > 1) {
+      // Pin can toggle between 0 and 1, so we need to wait for a few good
+      // frames before we start using the data.
+      break;
+    }
+  }
+
   while(1){
     this->blocks[0][--phase] =  port_in(this->p_pdm_mics);
 

python/mic_array/filters.py

@@ -78,13 +78,54 @@ def _pad_input(self, sig_in):
     S[:,P:] = sig_in
     return S
 
+  def boot_logic(self, pdm_signal: np.ndarray) -> np.ndarray:
+    # Simulate the PdmRx thread boot loop (StandardPdmRxService::ThreadEntry,
+    # PdmRx.hpp): words are received one at a time; 0x55555555 is written to
+    # the buffer (discarding real data) until good_frames > 1, i.e. 2
+    # consecutive words that are neither all-0 (0x00000000) nor all-1
+    # (0xFFFFFFFF). Bit layout: bit (c + CHANS*s) of word w =
+    # to_binary[c, w*spw+s], where to_binary(+1)=0, to_binary(-1)=1.
+
+    CHANS, SAMPS_IN = pdm_signal.shape
+    BOOT_WORD = np.uint32(0x55555555)
+    spw = 32 // CHANS  # PDM samples per channel packed per interleaved word
+    total_words = SAMPS_IN // spw
+    binary = ((1 - pdm_signal) // 2).astype(np.uint32)
+
+    words = np.zeros(total_words, dtype=np.uint32)
+    for s in range(spw):
+      for c in range(CHANS):
+        words |= binary[c, s::spw][:total_words] << np.uint32(c + CHANS * s)
+
+    good_frames = 0
+    boot_words = 0
+    for word in words:
+      boot_words += 1
+      if word == np.uint32(0x00000000) or word == np.uint32(0xFFFFFFFF):
+        good_frames = 0
+      else:
+        good_frames += 1
+      if good_frames > 1:
+        break
+
+    pdm_signal = pdm_signal.copy()
+    for w in range(boot_words):
+      for s in range(spw):
+        for c in range(CHANS):
+          bit = int((BOOT_WORD >> np.uint32(c + CHANS * s)) & np.uint32(1))
+          pdm_signal[c, w * spw + s] = np.int32(-1 if bit else 1)
+
+    return pdm_signal
+
   def FilterInt16(self, pdm_signal: np.ndarray) -> np.ndarray:
     if pdm_signal.ndim == 1:
       pdm_signal = pdm_signal[np.newaxis,:]
     CHANS, SAMPS_IN = pdm_signal.shape
     Q = self.DecimationFactor
     N_pcm = SAMPS_IN // self.DecimationFactor
 
+    pdm_signal = self.boot_logic(pdm_signal)
+
     S = self._pad_input(pdm_signal)
     coefs = self.Coef.astype(np.int32)[:,np.newaxis]
     res = np.empty((CHANS, N_pcm), dtype=np.int32)