doc/manual/jtag/drivers/remote_bitbang.txt

   1 /** @remote_bitbangpage OpenOCD Developer's Guide
   2
   3 The remote_bitbang JTAG+SWD driver is used to drive JTAG and/or SWD from a
   4 remote process. The remote_bitbang driver communicates via TCP or UNIX
   5 sockets with some remote process using an ASCII encoding of the bitbang
   6 interface. The remote process presumably then drives the JTAG/SWD however
   7 it pleases. The remote process should act as a server, listening for
   8 connections from the openocd remote_bitbang driver.
   9
  10 The remote bitbang driver is useful for debugging software running on
  11 processors which are being simulated.
  12
  13 There also is an implementation of the server-side protocol for the
  14 Glasgow Debug Tool (https://github.com/glasgowEmbedded/Glasgow) through
  15 the jtag-openocd applet.
  16
  17 The bitbang interface consists of the following functions.
  18
  19 blink on
  20         Blink a light somewhere. The argument on is either 1 or 0.
  21
  22 read
  23         Sample the value of tdo.
  24
  25 write tck tms tdi
  26         Set the value of tck, tms, and tdi.
  27
  28 reset trst srst
  29         Set the value of trst, srst.
  30
  31 swdio_drive
  32         Set the output enable of the bidirectional swdio (tms) pin
  33
  34 swdio_read
  35         Sample the value of swdio (tms).
  36
  37 swd_write
  38         Set the value of swclk (tck) and swdio (tms).
  39
  40 An additional function, quit, is added to the remote_bitbang interface to
  41 indicate there will be no more requests and the connection with the remote
  42 driver should be closed.
  43
  44 These eight functions are encoded in ASCII by assigning a single character to
  45 each possible request. The assignments are:
  46
  47         B - Blink on
  48         b - Blink off
  49         R - Read request
  50         Q - Quit request
  51         0 - Write 0 0 0
  52         1 - Write 0 0 1
  53         2 - Write 0 1 0
  54         3 - Write 0 1 1
  55         4 - Write 1 0 0
  56         5 - Write 1 0 1
  57         6 - Write 1 1 0
  58         7 - Write 1 1 1
  59         r - Reset 0 0
  60         s - Reset 0 1
  61         t - Reset 1 0
  62         u - Reset 1 1
  63         O - SWDIO drive 1
  64         o - SWDIO drive 0
  65         c - SWDIO read request
  66         d - SWD write 0 0
  67         e - SWD write 0 1
  68         f - SWD write 1 0
  69         g - SWD write 1 1
  70
  71 The read responses are encoded in ASCII as either digit 0 or 1.
  72
  73  */