/
PropOCD.spin
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PropOCD.spin
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{{
+-------------------------------------------------+
| OpenOCD Binary Protocol |
| Interface Object |
| |
| Authors: Ben Gardiner & Joe Grand |
| Copyright (c) 2020 Ben Gardiner & Joe Grand |
| |
| Distributed under a Creative Commons |
| Attribution 3.0 United States license |
| http://creativecommons.org/licenses/by/3.0/us/ |
+-------------------------------------------------+
Program Description:
This object provides the low-level communication interface for OpenOCD. It emulates
the binary protocol used by the Bus Pirate (http://dangerousprototypes.com/docs/Bus_Pirate#JTAG
and https://github.com/DangerousPrototypes/Bus_Pirate/blob/master/Firmware/OpenOCD.c)
}}
CON
' Serial terminal
BaudRate = 115_200
RxPin = |<31
TxPin = |<30
' Control characters
CAN = 24 ''CAN: Cancel (Ctrl-X)
MAX_RX_DELAY_MS = 100 ' Wait time (in ms) for the each byte in commands to be sent before aborting
CMD_UNKNOWN = $00
CMD_PORT_MODE = $01 ' port type
CMD_FEATURE = $02 ' hardware-specific configuration
CMD_READ_ADCS = $03 ' read A/Ds
'CMD_TAP_SHIFT = $04 ' shift TAP (old protocol)
CMD_TAP_SHIFT = $05 ' shift TAP
CMD_ENTER_OOCD = $06 ' enter binary (OCD) mode
CMD_UART_SPEED = $07 ' UART speed select
CMD_JTAG_SPEED = $08 ' JTAG speed select
CMD_RESET = $0F ' reset (from buspirate_jtag_reset in OpenOCD buspirate.c)
FEATURE_LED = $01 ' LED on/off
FEATURE_VREG = $02 ' voltage regulator on/off
FEATURE_TRST = $04 ' set TRST logic state
FEATURE_SRST = $08 ' set SRST logic state
FEATURE_PULLUP = $10 ' pull up resistors on/off
SERIAL_NORMAL = 0
SERIAL_FAST = 1 ' ~1 MHz
MODE_HIZ = 0 ' high impedance (hi Z), input
MODE_JTAG = 1 ' push-pull, output
MODE_JTAG_OD = 2 ' open drain, output
MAX_BIT_SEQUENCES = 8192 ' Maximum number of bit sequences allowed per CMD_TAP_SHIFT
VAR
long vCmd ' Address of global buffer from top object
OBJ
g : "JTAGulatorCon" ' JTAGulator global constants
u : "JTAGulatorUtil" ' JTAGulator general purpose utilities
pst : "JDCogSerial" ' UART/Asynchronous Serial communication engine (Carl Jacobs, http://obex.parallax.com/object/298)
jtag : "PropJTAG" ' JTAG/IEEE 1149.1 low-level methods
PUB Go(tdi, tdo, tck, tms, bufPtr) | ctr
pst.Start(RxPin, TxPin, BaudRate) ' Configure UART
vCmd := bufPtr
u.LEDRed ' We are initialized and ready to go
u.TXSEnable ' Enable level shifter outputs
u.Set_Pins_High(0, g#MAX_CHAN) ' In case there is a signal on the target that needs to be held HIGH, like TRST# or SRST#
jtag.Config(tdi, tdo, tck, tms) ' Configure JTAG
' Start command receive/process cycle
repeat
byte[vCmd][0]:=pst.Rx
case byte[vCmd][0]
CAN: ' If Ctrl-X (CAN) character received, exit OpenOCD mode
pst.Stop ' Stop serial communications
return ' Go back to main JTAGulator mode
'the 'short' commands follow; all are 1 byte, no parameters
CMD_UNKNOWN: ' From buspirate_bbio_enable and buspirate_jtag_reset in OpenOCD buspirate.c
u.LEDRed ' Ensure LED turns back to red when OpenOCD is closed
pst.Str(@BBIO)
CMD_ENTER_OOCD:
pst.Str(@OCD)
CMD_READ_ADCS: ' Not supported
pst.Tx(CMD_READ_ADCS) ' Send acknowledgement
pst.Tx(8) ' Number of bytes
repeat 8
pst.Tx(0)
'remaining commands are 'long' commands, which take 1 or more parameters
CMD_PORT_MODE: ' Not supported
if (GetMoreParamBytes(1) == -1)
next
case byte[vCmd][1]
MODE_HIZ:
next
MODE_JTAG:
next
MODE_JTAG_OD:
next
CMD_FEATURE:
if (GetMoreParamBytes(2) == -1)
pst.Tx(0)
next
case byte[vCmd][1]
FEATURE_LED:
next
FEATURE_VREG:
next
FEATURE_TRST:
next
FEATURE_SRST:
next
FEATURE_PULLUP:
next
CMD_JTAG_SPEED: ' Not supported
if (GetMoreParamBytes(2) == -1)
next
CMD_UART_SPEED: ' Not supported
if (GetMoreParamBytes(1) == -1)
pst.Tx(0)
next
pst.Tx(CMD_UART_SPEED) ' Send acknowledgement
pst.Tx(SERIAL_NORMAL)
CMD_TAP_SHIFT:
if (++ctr // 10) == 0
!outa[g#LED_G] ' Toggle LED between red and yellow
if (GetMoreParamBytes(2) == -1)
pst.Tx(0)
Do_Tap_Shift
CMD_RESET:
next
other: ' Invalid byte
pst.Tx(0)
PRI Do_Tap_Shift | num_sequences, num_bytes, bits, value, i
' based on HydraBus implementation of Bus Pirate binary protocol
' https://github.com/hydrabus/hydrafw/blob/master/src/hydrabus/hydrabus_mode_jtag.c
' calculate number of requested bit sequences
num_sequences := byte[vCmd][1]
num_sequences <<= 8
num_sequences |= byte[vCmd][2]
if num_sequences > MAX_BIT_SEQUENCES ' Upper bounds check
num_sequences := MAX_BIT_SEQUENCES
pst.Tx(CMD_TAP_SHIFT) ' Send acknowledgement
pst.Tx(byte[vCmd][1])
pst.Tx(byte[vCmd][2])
' calculate number of bytes to read
num_bytes := ((num_sequences + 7) / 8) * 2
' get bytes from OpenOCD with the TDI and TMS data to shift into target
if (GetMoreParamBytes(num_bytes) == -1)
pst.Tx(0)
return ' exit if we don't receive the correct number of bytes
i := 0
repeat while (num_sequences > 0)
if (num_sequences > 8) ' Do 8 bits at a time until the last set
bits := 8
else
bits := num_sequences
value := OpenOCD_Shift(byte[vCmd][i+1] {TDI}, byte[vCmd][i+2] {TMS}, bits)
pst.Tx(value & $FF)
i += 2
num_sequences -= bits
PRI OpenOCD_Shift(ocd_tdi, ocd_tms, num_bits) : ocd_tdo | num ' Shift data from OpenOCD into target and receive result
num := num_bits
repeat while (num_bits > 0)
if (ocd_tms & 1)
jtag.TMS_High
else
jtag.TMS_Low
if (ocd_tdi & 1)
jtag.TDI_High
else
jtag.TDI_Low
ocd_tdo <<= 1
ocd_tdo |= jtag.TDO_Read
ocd_tdi >>= 1 ' Shift to the next bit in the sequence
ocd_tms >>= 1
num_bits -= 1 ' Adjust number of remaining bits
ocd_tdo ><= num ' Bitwise reverse since LSB came in first (we want MSB to be first)
PRI GetMoreParamBytes(num) : val | i
repeat i from 1 to num
if (byte[vCmd][i]:=pst.RxTime(MAX_RX_DELAY_MS)) < 0
val:=-1
DAT
ORG
BBIO byte "BBIO1", 0
OCD byte "OCD1", 0