From b5712ccbbcd023e5ac20d790bf75af3c18fc66d5 Mon Sep 17 00:00:00 2001 From: Petteri Aimonen Date: Sun, 15 Feb 2015 19:08:36 +0200 Subject: Improve uart decoder sample positions at high data rates. At 3 samples per bit, the uart decoder took the value at the last sample instead of the middle one. Improve calculations so that sampling is more accurate at odd number of samples per bit. --- decoders/uart/pd.py | 25 ++++++++++++++----------- 1 file changed, 14 insertions(+), 11 deletions(-) (limited to 'decoders') diff --git a/decoders/uart/pd.py b/decoders/uart/pd.py index d59c6c3..7995e99 100644 --- a/decoders/uart/pd.py +++ b/decoders/uart/pd.py @@ -19,6 +19,7 @@ ## import sigrokdecode as srd +from math import floor, ceil ''' OUTPUT_PYTHON format: @@ -139,24 +140,24 @@ class Decoder(srd.Decoder): ) def putx(self, rxtx, data): - s, halfbit = self.startsample[rxtx], int(self.bit_width / 2) - self.put(s - halfbit, self.samplenum + halfbit, self.out_ann, data) + s, halfbit = self.startsample[rxtx], self.bit_width / 2.0 + self.put(s - floor(halfbit), self.samplenum + ceil(halfbit), self.out_ann, data) def putpx(self, rxtx, data): - s, halfbit = self.startsample[rxtx], int(self.bit_width / 2) - self.put(s - halfbit, self.samplenum + halfbit, self.out_python, data) + s, halfbit = self.startsample[rxtx], self.bit_width / 2.0 + self.put(s - floor(halfbit), self.samplenum + ceil(halfbit), self.out_python, data) def putg(self, data): - s, halfbit = self.samplenum, int(self.bit_width / 2) - self.put(s - halfbit, s + halfbit, self.out_ann, data) + s, halfbit = self.samplenum, self.bit_width / 2.0 + self.put(s - floor(halfbit), s + ceil(halfbit), self.out_ann, data) def putp(self, data): - s, halfbit = self.samplenum, int(self.bit_width / 2) - self.put(s - halfbit, s + halfbit, self.out_python, data) + s, halfbit = self.samplenum, self.bit_width / 2.0 + self.put(s - floor(halfbit), s + ceil(halfbit), self.out_python, data) def putbin(self, rxtx, data): - s, halfbit = self.startsample[rxtx], int(self.bit_width / 2) - self.put(s - halfbit, self.samplenum + halfbit, self.out_bin, data) + s, halfbit = self.startsample[rxtx], self.bit_width / 2.0 + self.put(s - floor(halfbit), self.samplenum + ceil(halfbit), self.out_bin, data) def __init__(self, **kwargs): self.samplerate = None @@ -189,7 +190,9 @@ class Decoder(srd.Decoder): # bitpos is the samplenumber which is in the middle of the # specified UART bit (0 = start bit, 1..x = data, x+1 = parity bit # (if used) or the first stop bit, and so on). - bitpos = self.frame_start[rxtx] + (self.bit_width / 2.0) + # The samples within bit are 0, 1, ..., (bit_width - 1), therefore + # index of the middle sample within bit window is (bit_width - 1) / 2. + bitpos = self.frame_start[rxtx] + (self.bit_width - 1) / 2.0 bitpos += bitnum * self.bit_width if self.samplenum >= bitpos: return True -- cgit v1.2.3-70-g09d2