All PDs: Improve/fix descriptions.

1 files changed, 22 insertions, 0 deletions

diff --git a/decoders/jtag/pd.py b/decoders/jtag/pd.py
index 55a9a1f..ea6887b 100644
--- a/decoders/jtag/pd.py
+++ b/decoders/jtag/pd.py
@@ -22,6 +22,28 @@
 
 import sigrokdecode as srd
 
+'''
+Protocol output format:
+
+JTAG packet:
+[<packet-type>, <data>]
+
+<packet-type> is one of:
+ - 'NEW STATE': <data> is the new state of the JTAG state machine.
+   Valid values: 'TEST-LOGIC-RESET', 'RUN-TEST/IDLE', 'SELECT-DR-SCAN',
+   'CAPTURE-DR', 'SHIFT-DR', 'EXIT1-DR', 'PAUSE-DR', 'EXIT2-DR', 'UPDATE-DR',
+   'SELECT-IR-SCAN', 'CAPTURE-IR', 'SHIFT-IR', 'EXIT1-IR', 'PAUSE-IR',
+   'EXIT2-IR', 'UPDATE-IR'.
+ - 'IR TDI': Bitstring that was clocked into the IR register.
+ - 'IR TDO': Bitstring that was clocked out of the IR register.
+ - 'DR TDI': Bitstring that was clocked into the DR register.
+ - 'DR TDO': Bitstring that was clocked out of the DR register.
+ - ...
+
+All bitstrings are a sequence of '1' and '0' characters. The right-most
+character in the bitstring is the LSB. Example: '01110001' (1 is LSB).
+'''
+
 jtag_states = [
         # Intro "tree"
         'TEST-LOGIC-RESET', 'RUN-TEST/IDLE',