X-Git-Url: https://sigrok.org/gitweb/?a=blobdiff_plain;f=decoders%2Fjtag%2F__init__.py;h=4a53502a48b794a0d9bf4f39f1eaec7c418a085e;hb=e540618c9d8d04ebb2e639ad1e650d689c89a818;hp=21ec679358a1e76cbf14949607e431306e3ed53a;hpb=557a143d8018ac5b25b0cdde99415433e3663f62;p=libsigrokdecode.git

diff --git a/decoders/jtag/__init__.py b/decoders/jtag/__init__.py
index 21ec679..4a53502 100644
--- a/decoders/jtag/__init__.py
+++ b/decoders/jtag/__init__.py
@@ -21,8 +21,35 @@
 '''
 JTAG protocol decoder.
 
+JTAG (Joint Test Action Group), a.k.a. "IEEE 1149.1: Standard Test Access Port
+and Boundary-Scan Architecture", is a protocol used for testing, debugging,
+and flashing various digital ICs.
+
+TODO: Protocol details.
+
+Protocol output format (WORK IN PROGRESS!):
+
+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).
+
 Details:
-TODO
+https://en.wikipedia.org/wiki/Joint_Test_Action_Group
+http://focus.ti.com/lit/an/ssya002c/ssya002c.pdf
 '''
 
 from .jtag import *