X-Git-Url: https://sigrok.org/gitweb/?p=libsigrokdecode.git;a=blobdiff_plain;f=decoders%2Fusb%2Fusb.py;h=529868e2121ea6cb86ff07ccc1fcd992f0136723;hp=8620de0f576afe2351164eb7d5775f2573ee8cfb;hb=3cf771a5179d94a156bef1aa95d7e05411dc82e2;hpb=a465436e627578f69c403de75a89522dfd883217 diff --git a/decoders/usb/usb.py b/decoders/usb/usb.py index 8620de0..529868e 100644 --- a/decoders/usb/usb.py +++ b/decoders/usb/usb.py @@ -18,32 +18,67 @@ ## Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA ## -# USB (full-speed) protocol decoder +# USB (low-speed and full-speed) protocol decoder import sigrokdecode as srd -# Symbols (used as states of our state machine, too) +# Full-speed symbols (used as states of our state machine, too). +# Note: Low-speed J and K are inverted compared to the full-speed J and K! syms = { + # (, ): (0, 0): 'SE0', (1, 0): 'J', (0, 1): 'K', (1, 1): 'SE1', } -# ... +# Packet IDs (PIDs). +# The first 4 bits are the 'packet type' field, the last 4 bits are the +# 'check field' (each bit in the check field must be the inverse of the resp. +# bit in the 'packet type' field; if not, that's a 'PID error'). +# For the 4-bit strings, the left-most '1' or '0' is the LSB, i.e. it's sent +# to the bus first. pids = { - '10000111': 'OUT', # Tokens - '10010110': 'IN', - '10100101': 'SOF', - '10110100': 'SETUP', - '11000011': 'DATA0', # Data - '11010010': 'DATA1', - '01001011': 'ACK', # Handshake - '01011010': 'NAK', - '01111000': 'STALL', - '01101001': 'NYET', + # Tokens + '10000111': ['OUT', 'Address & EP number in host-to-function transaction'], + '10010110': ['IN', 'Address & EP number in function-to-host transaction'], + '10100101': ['SOF', 'Start-Of-Frame marker & frame number'], + '10110100': ['SETUP', 'Address & EP number in host-to-function transaction for SETUP to a control pipe'], + + # Data + # Note: DATA2 and MDATA are HS-only. + '11000011': ['DATA0', 'Data packet PID even'], + '11010010': ['DATA1', 'Data packet PID odd'], + '11100001': ['DATA2', 'Data packet PID HS, high bandwidth isosynchronous transaction in a microframe'], + '11110000': ['MDATA', 'Data packet PID HS for split and high-bandwidth isosynchronous transactions'], + + # Handshake + '01001011': ['ACK', 'Receiver accepts error-free packet'], + '01011010': ['NAK', 'Receiver cannot accept or transmitter cannot send'], + '01111000': ['STALL', 'EP halted or control pipe request unsupported'], + '01101001': ['NYET', 'No response yet from receiver'], + + # Special + '00111100': ['PRE', 'Host-issued preamble; enables downstream bus traffic to low-speed devices'], + '00111100': ['ERR', 'Split transaction error handshake'], + '00011110': ['SPLIT', 'HS split transaction token'], + '00101101': ['PING', 'HS flow control probe for a bulk/control EP'], + '00001111': ['Reserved', 'Reserved PID'], } +def get_sym(signalling, dp, dm): + # Note: Low-speed J and K are inverted compared to the full-speed J and K! + if signalling == 'low-speed': + s = syms[dp, dm] + if s == 'J': + return 'K' + elif s == 'K': + return 'J' + else: + return s + elif signalling == 'full-speed': + return syms[dp, dm] + def bitstr_to_num(bitstr): if not bitstr: return 0 @@ -54,7 +89,7 @@ def bitstr_to_num(bitstr): def packet_decode(packet): sync = packet[:8] pid = packet[8:16] - pid = pids.get(pid, pid) + pid = pids.get(pid, (pid, ''))[0] # Remove CRC. if pid in ('OUT', 'IN', 'SOF', 'SETUP'): @@ -65,7 +100,6 @@ def packet_decode(packet): dev = bitstr_to_num(data[:7]) ep = bitstr_to_num(data[7:]) data = 'DEV %d EP %d' % (dev, ep) - elif pid in ('DATA0', 'DATA1'): data = packet[16:-16] tmp = '' @@ -76,6 +110,7 @@ def packet_decode(packet): else: data = packet[16:] + # The SYNC pattern for low-speed/full-speed is KJKJKJKK (0001). if sync != '00000001': return 'SYNC INVALID!' @@ -85,8 +120,8 @@ class Decoder(srd.Decoder): api_version = 1 id = 'usb' name = 'USB' - longname = 'Universal Serial Bus' - desc = 'USB 1.x (full-speed) serial protocol.' + longname = 'Universal Serial Bus (LS/FS)' + desc = 'USB 1.x (low-speed and full-speed) serial protocol.' license = 'gplv2+' inputs = ['logic'] outputs = ['usb'] @@ -95,13 +130,18 @@ class Decoder(srd.Decoder): {'id': 'dm', 'name': 'D-', 'desc': 'USB D- signal'}, ] optional_probes = [] - options = {} + options = { + 'signalling': ['Signalling', 'full-speed'], + } annotations = [ ['Text', 'Human-readable text'] ] def __init__(self): - pass + self.sym = 'J' + self.samplenum = 0 + self.scount = 0 + self.packet = '' def start(self, metadata): self.samplerate = metadata['samplerate'] @@ -109,37 +149,37 @@ class Decoder(srd.Decoder): # self.out_proto = self.add(srd.OUTPUT_PROTO, 'usb') self.out_ann = self.add(srd.OUTPUT_ANN, 'usb') - if self.samplerate < 48000000: - raise Exception('Samplerate (%d) not sufficient for USB ' - 'decoding, need at least 48MHz' % self.samplerate) - - # Initialise decoder state. - self.sym = 'J' - self.samplenum = 0 - self.packet = '' - def report(self): pass def decode(self, ss, es, data): - for (self.samplenum, (dm, dp)) in data: + for (self.samplenum, (dp, dm)) in data: + + # Note: self.samplenum is the absolute sample number, whereas + # self.scount only counts the number of samples since the + # last change in the D+/D- lines. + self.scount += 1 - sym = syms[dp, dm] + sym = get_sym(self.options['signalling'], dp, dm) - # ... + # Wait for a symbol change (i.e., change in D+/D- lines). if sym == self.sym: continue - if self.samplenum == 1: - # We ignore single sample width pulses. - # I sometimes get these with the OLS. + if self.scount == 1: + # We ignore single sample width "pulses", i.e., symbol changes + # (D+/D- line changes). I sometimes get these with the OLS. self.sym = sym - self.samplenum = 0 + self.scount = 0 continue # How many bits since the last transition? if self.packet != '' or self.sym != 'J': - bitcount = int((self.samplenum - 1) * 12000000 / self.samplerate) + if self.options['signalling'] == 'low-speed': + bitrate = 1500000 # 1.5Mb/s (+/- 1.5%) + elif self.options['signalling'] == 'full-speed': + bitrate = 12000000 # 12Mb/s (+/- 0.25%) + bitcount = int((self.scount - 1) * bitrate / self.samplerate) else: bitcount = 0 @@ -151,7 +191,7 @@ class Decoder(srd.Decoder): else: # Longer than EOP, assume reset. self.put(0, 0, self.out_ann, [0, ['RESET']]) - self.samplenum = 0 + self.scount = 0 self.sym = sym self.packet = '' continue @@ -165,6 +205,6 @@ class Decoder(srd.Decoder): elif bitcount > 6: self.put(0, 0, self.out_ann, [0, ['BIT STUFF ERROR']]) - self.samplenum = 0 + self.scount = 0 self.sym = sym