[libsigrokdecode.git] / decoders / avr_isp / pd.py

##
## This file is part of the libsigrokdecode project.
##
## Copyright (C) 2012-2014 Uwe Hermann <uwe@hermann-uwe.de>
##
## This program is free software; you can redistribute it and/or modify
## it under the terms of the GNU General Public License as published by
## the Free Software Foundation; either version 2 of the License, or
## (at your option) any later version.
##
## This program is distributed in the hope that it will be useful,
## but WITHOUT ANY WARRANTY; without even the implied warranty of
## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
## GNU General Public License for more details.
##
## You should have received a copy of the GNU General Public License
## along with this program; if not, see <http://www.gnu.org/licenses/>.
##

import sigrokdecode as srd
from .parts import *

class Ann:
    PE, RSB0, RSB1, RSB2, CE, RFB, RHFB, REFB, \
    RLB, REEM, RP, LPMP, WP, WARN, DEV, = range(15)

VENDOR_CODE_ATMEL = 0x1e

class Decoder(srd.Decoder):
    api_version = 3
    id = 'avr_isp'
    name = 'AVR ISP'
    longname = 'AVR In-System Programming'
    desc = 'Atmel AVR In-System Programming (ISP) protocol.'
    license = 'gplv2+'
    inputs = ['spi']
    outputs = []
    tags = ['Debug/trace']
    annotations = (
        ('pe', 'Programming enable'),
        ('rsb0', 'Read signature byte 0'),
        ('rsb1', 'Read signature byte 1'),
        ('rsb2', 'Read signature byte 2'),
        ('ce', 'Chip erase'),
        ('rfb', 'Read fuse bits'),
        ('rhfb', 'Read high fuse bits'),
        ('refb', 'Read extended fuse bits'),
        ('rlb', 'Read lock bits'),
        ('reem', 'Read EEPROM memory'),
        ('rp', 'Read program memory'),
        ('lpmp' , 'Load program memory page'),
        ('wp', 'Write program memory'),
        ('warning', 'Warning'),
        ('dev', 'Device'),
    )
    annotation_rows = (
        ('commands', 'Commands', (Ann.PE, Ann.RSB0, Ann.RSB1, Ann.RSB2,
            Ann.CE, Ann.RFB, Ann.RHFB, Ann.REFB,
            Ann.RLB, Ann.REEM, Ann.RP, Ann.LPMP, Ann.WP,)),
        ('warnings', 'Warnings', (Ann.WARN,)),
        ('devs', 'Devices', (Ann.DEV,)),
    )

    def __init__(self):
        self.reset()

    def reset(self):
        self.state = 'IDLE'
        self.mosi_bytes, self.miso_bytes = [], []
        self.ss_cmd, self.es_cmd = 0, 0
        self.xx, self.yy, self.zz, self.mm = 0, 0, 0, 0
        self.ss_device = None

    def start(self):
        self.out_ann = self.register(srd.OUTPUT_ANN)

    def putx(self, data):
        self.put(self.ss_cmd, self.es_cmd, self.out_ann, data)

    def handle_cmd_programming_enable(self, cmd, ret):
        # Programming enable.
        # Note: The chip doesn't send any ACK for 'Programming enable'.
        self.putx([Ann.PE, ['Programming enable']])

        # Sanity check on reply.
        if ret[1:4] != [0xac, 0x53, cmd[2]]:
            self.putx([Ann.WARN, ['Warning: Unexpected bytes in reply!']])

    def handle_cmd_read_signature_byte_0x00(self, cmd, ret):
        # Signature byte 0x00: vendor code.
        self.vendor_code = ret[3]
        v = vendor_code[self.vendor_code]
        self.putx([Ann.RSB0, ['Vendor code: 0x%02x (%s)' % (ret[3], v)]])

        # Store for later.
        self.xx = cmd[1] # Same as ret[2].
        self.yy = cmd[3]
        self.zz = ret[0]

        # Sanity check on reply.
        if ret[1] != 0x30 or ret[2] != cmd[1]:
            self.putx([Ann.WARN, ['Warning: Unexpected bytes in reply!']])

        # Sanity check for the vendor code.
        if self.vendor_code != VENDOR_CODE_ATMEL:
            self.putx([Ann.WARN, ['Warning: Vendor code was not 0x1e (Atmel)!']])

    def handle_cmd_read_signature_byte_0x01(self, cmd, ret):
        # Signature byte 0x01: part family and memory size.
        self.part_fam_flash_size = ret[3]
        self.putx([Ann.RSB1, ['Part family / memory size: 0x%02x' % ret[3]]])

        # Store for later.
        self.mm = cmd[3]
        self.ss_device = self.ss_cmd

        # Sanity check on reply.
        if ret[1] != 0x30 or ret[2] != cmd[1] or ret[0] != self.yy:
            self.putx([Ann.WARN, ['Warning: Unexpected bytes in reply!']])

    def handle_cmd_read_signature_byte_0x02(self, cmd, ret):
        # Signature byte 0x02: part number.
        self.part_number = ret[3]
        self.putx([Ann.RSB2, ['Part number: 0x%02x' % ret[3]]])

        # Part name if known
        key = (self.part_fam_flash_size, self.part_number)
        if key in part:
            p = part[key]
            data = [Ann.DEV, ['Device: Atmel %s' % p]]
            self.put(self.ss_device, self.es_cmd, self.out_ann, data)

        # Sanity check on reply.
        if ret[1] != 0x30 or ret[2] != self.xx or ret[0] != self.mm:
            self.putx([Ann.WARN, ['Warning: Unexpected bytes in reply!']])

        self.xx, self.yy, self.zz, self.mm = 0, 0, 0, 0

    def handle_cmd_chip_erase(self, cmd, ret):
        # Chip erase (erases both flash an EEPROM).
        # Upon successful chip erase, the lock bits will also be erased.
        # The only way to end a Chip Erase cycle is to release RESET#.
        self.putx([Ann.CE, ['Chip erase']])

        # TODO: Check/handle RESET#.

        # Sanity check on reply.
        bit = (ret[2] & (1 << 7)) >> 7
        if ret[1] != 0xac or bit != 1 or ret[3] != cmd[2]:
            self.putx([Ann.WARN, ['Warning: Unexpected bytes in reply!']])

    def handle_cmd_read_fuse_bits(self, cmd, ret):
        # Read fuse bits.
        self.putx([Ann.RFB, ['Read fuse bits: 0x%02x' % ret[3]]])

        # TODO: Decode fuse bits.
        # TODO: Sanity check on reply.

    def handle_cmd_read_fuse_high_bits(self, cmd, ret):
        # Read fuse high bits.
        self.putx([Ann.RHFB, ['Read fuse high bits: 0x%02x' % ret[3]]])

        # TODO: Decode fuse bits.
        # TODO: Sanity check on reply.

    def handle_cmd_read_extended_fuse_bits(self, cmd, ret):
        # Read extended fuse bits.
        self.putx([Ann.REFB, ['Read extended fuse bits: 0x%02x' % ret[3]]])

        # TODO: Decode fuse bits.
        # TODO: Sanity check on reply.

    def handle_cmd_read_lock_bits(self, cmd, ret):
        # Read lock bits
        self.putx([Ann.RLB, ['Read lock bits: 0x%02x' % ret[3]]])

    def handle_cmd_read_eeprom_memory(self, cmd, ret):
        # Read EEPROM Memory
        _addr = ((cmd[1] & 1) << 8) + cmd[2]
        self.putx([Ann.REEM, ['Read EEPROM Memory: [0x%03x]: 0x%02x' % (_addr, ret[3])]])

    def handle_cmd_read_program_memory(self, cmd, ret):
        # Read Program Memory
        _HL = 'Low'
        _H = 'L'
        if cmd[0] & 0x08:
            _HL = 'High'
            _H = 'H'
        _addr = ((cmd[1] & 0x0f) << 8) + cmd[2]
        self.putx([Ann.RP, [
            'Read program memory %s: [0x%03x]: 0x%02x' % (_HL, _addr, ret[3]),
            '[%03x%s]:%02x' % (_addr, _H, ret[3]),
            '%02x' % ret[3]
        ]])

    def handle_cmd_load_program_memory_page(self, cmd, ret):
        # Load Program Memory Page
        _HL = 'Low'
        _H = 'L'
        if cmd[0] & 0x08:
            _HL = 'High'
            _H = 'H'
        _addr = cmd[2] & 0x1F
        self.putx([Ann.LPMP, [
            'Load program memory page %s: [0x%03x]: 0x%02x' % (_HL, _addr, cmd[3]),
            '[%03x%s]=%02x' % (_addr, _H, cmd[3]),
            '%02x' % cmd[3]
        ]])

    def handle_cmd_write_program_memory_page(self, cmd, ret):
        # Write Program Memory Page
        _addr = ((cmd[1] & 0x0F) << 3) + (cmd[2] << 5)
        self.putx([Ann.WP, ['Write program memory page: 0x%02x' % _addr]])

    def handle_command(self, cmd, ret):
        if cmd[:2] == [0xac, 0x53]:
            self.handle_cmd_programming_enable(cmd, ret)
        elif cmd[0] == 0xac and (cmd[1] & (1 << 7)) == (1 << 7):
            self.handle_cmd_chip_erase(cmd, ret)
        elif cmd[:3] == [0x50, 0x00, 0x00]:
            self.handle_cmd_read_fuse_bits(cmd, ret)
        elif cmd[:3] == [0x58, 0x08, 0x00]:
            self.handle_cmd_read_fuse_high_bits(cmd, ret)
        elif cmd[:3] == [0x50, 0x08, 0x00]:
            self.handle_cmd_read_extended_fuse_bits(cmd, ret)
        elif cmd[0] == 0x30 and cmd[2] == 0x00:
            self.handle_cmd_read_signature_byte_0x00(cmd, ret)
        elif cmd[0] == 0x30 and cmd[2] == 0x01:
            self.handle_cmd_read_signature_byte_0x01(cmd, ret)
        elif cmd[0] == 0x30 and cmd[2] == 0x02:
            self.handle_cmd_read_signature_byte_0x02(cmd, ret)
        elif cmd[:2] == [0x58, 0x00]:
            self.handle_cmd_read_lock_bits(cmd,ret)
        elif cmd[0] == 0xa0 and (cmd[1] & (3 << 6)) == (0 << 6):
            self.handle_cmd_read_eeprom_memory(cmd, ret)
        elif (cmd[0] == 0x20 or cmd[0] == 0x28) and ((cmd[1] & 0xf0) == 0x00):
            self.handle_cmd_read_program_memory(cmd, ret)
        elif (cmd[0] == 0x40 or cmd[0] == 0x48) and ((cmd[1] & 0xf0) == 0x00):
            self.handle_cmd_load_program_memory_page(cmd, ret)
        elif (cmd[0] == 0x4C and ((cmd[1] & 0xf0) == 0x00)):
            self.handle_cmd_write_program_memory_page(cmd, ret)
        else:
            c = '%02x %02x %02x %02x' % tuple(cmd)
            r = '%02x %02x %02x %02x' % tuple(ret)
            self.putx([Ann.WARN, ['Unknown command: %s (reply: %s)!' % (c, r)]])

    def decode(self, ss, es, data):
        ptype, mosi, miso = data

        # For now, only use DATA and BITS packets.
        if ptype not in ('DATA', 'BITS'):
            return

        # Store the individual bit values and ss/es numbers. The next packet
        # is guaranteed to be a 'DATA' packet belonging to this 'BITS' one.
        if ptype == 'BITS':
            self.miso_bits, self.mosi_bits = miso, mosi
            return

        self.ss, self.es = ss, es

        if len(self.mosi_bytes) == 0:
            self.ss_cmd = ss

        # Append new bytes.
        self.mosi_bytes.append(mosi)
        self.miso_bytes.append(miso)

        # All commands consist of 4 bytes.
        if len(self.mosi_bytes) < 4:
            return

        self.es_cmd = es

        self.handle_command(self.mosi_bytes, self.miso_bytes)

        self.mosi_bytes = []
        self.miso_bytes = []
Commit	Line	Data
	1	##
	2	## This file is part of the libsigrokdecode project.
	3	##
	4	## Copyright (C) 2012-2014 Uwe Hermann <uwe@hermann-uwe.de>
	5	##
	6	## This program is free software; you can redistribute it and/or modify
	7	## it under the terms of the GNU General Public License as published by
	8	## the Free Software Foundation; either version 2 of the License, or
	9	## (at your option) any later version.
	10	##
	11	## This program is distributed in the hope that it will be useful,
	12	## but WITHOUT ANY WARRANTY; without even the implied warranty of
	13	## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	14	## GNU General Public License for more details.
	15	##
	16	## You should have received a copy of the GNU General Public License
	17	## along with this program; if not, see <http://www.gnu.org/licenses/>.
	18	##
	19
	20	import sigrokdecode as srd
	21	from .parts import *
	22
	23	class Ann:
	24	PE, RSB0, RSB1, RSB2, CE, RFB, RHFB, REFB, \
	25	RLB, REEM, RP, LPMP, WP, WARN, DEV, = range(15)
	26
	27	VENDOR_CODE_ATMEL = 0x1e
	28
	29	class Decoder(srd.Decoder):
	30	api_version = 3
	31	id = 'avr_isp'
	32	name = 'AVR ISP'
	33	longname = 'AVR In-System Programming'
	34	desc = 'Atmel AVR In-System Programming (ISP) protocol.'
	35	license = 'gplv2+'
	36	inputs = ['spi']
	37	outputs = []
	38	tags = ['Debug/trace']
	39	annotations = (
	40	('pe', 'Programming enable'),
	41	('rsb0', 'Read signature byte 0'),
	42	('rsb1', 'Read signature byte 1'),
	43	('rsb2', 'Read signature byte 2'),
	44	('ce', 'Chip erase'),
	45	('rfb', 'Read fuse bits'),
	46	('rhfb', 'Read high fuse bits'),
	47	('refb', 'Read extended fuse bits'),
	48	('rlb', 'Read lock bits'),
	49	('reem', 'Read EEPROM memory'),
	50	('rp', 'Read program memory'),
	51	('lpmp' , 'Load program memory page'),
	52	('wp', 'Write program memory'),
	53	('warning', 'Warning'),
	54	('dev', 'Device'),
	55	)
	56	annotation_rows = (
	57	('commands', 'Commands', (Ann.PE, Ann.RSB0, Ann.RSB1, Ann.RSB2,
	58	Ann.CE, Ann.RFB, Ann.RHFB, Ann.REFB,
	59	Ann.RLB, Ann.REEM, Ann.RP, Ann.LPMP, Ann.WP,)),
	60	('warnings', 'Warnings', (Ann.WARN,)),
	61	('devs', 'Devices', (Ann.DEV,)),
	62	)
	63
	64	def __init__(self):
	65	self.reset()
	66
	67	def reset(self):
	68	self.state = 'IDLE'
	69	self.mosi_bytes, self.miso_bytes = [], []
	70	self.ss_cmd, self.es_cmd = 0, 0
	71	self.xx, self.yy, self.zz, self.mm = 0, 0, 0, 0
	72	self.ss_device = None
	73
	74	def start(self):
	75	self.out_ann = self.register(srd.OUTPUT_ANN)
	76
	77	def putx(self, data):
	78	self.put(self.ss_cmd, self.es_cmd, self.out_ann, data)
	79
	80	def handle_cmd_programming_enable(self, cmd, ret):
	81	# Programming enable.
	82	# Note: The chip doesn't send any ACK for 'Programming enable'.
	83	self.putx([Ann.PE, ['Programming enable']])
	84
	85	# Sanity check on reply.
	86	if ret[1:4] != [0xac, 0x53, cmd[2]]:
	87	self.putx([Ann.WARN, ['Warning: Unexpected bytes in reply!']])
	88
	89	def handle_cmd_read_signature_byte_0x00(self, cmd, ret):
	90	# Signature byte 0x00: vendor code.
	91	self.vendor_code = ret[3]
	92	v = vendor_code[self.vendor_code]
	93	self.putx([Ann.RSB0, ['Vendor code: 0x%02x (%s)' % (ret[3], v)]])
	94
	95	# Store for later.
	96	self.xx = cmd[1] # Same as ret[2].
	97	self.yy = cmd[3]
	98	self.zz = ret[0]
	99
	100	# Sanity check on reply.
	101	if ret[1] != 0x30 or ret[2] != cmd[1]:
	102	self.putx([Ann.WARN, ['Warning: Unexpected bytes in reply!']])
	103
	104	# Sanity check for the vendor code.
	105	if self.vendor_code != VENDOR_CODE_ATMEL:
	106	self.putx([Ann.WARN, ['Warning: Vendor code was not 0x1e (Atmel)!']])
	107
	108	def handle_cmd_read_signature_byte_0x01(self, cmd, ret):
	109	# Signature byte 0x01: part family and memory size.
	110	self.part_fam_flash_size = ret[3]
	111	self.putx([Ann.RSB1, ['Part family / memory size: 0x%02x' % ret[3]]])
	112
	113	# Store for later.
	114	self.mm = cmd[3]
	115	self.ss_device = self.ss_cmd
	116
	117	# Sanity check on reply.
	118	if ret[1] != 0x30 or ret[2] != cmd[1] or ret[0] != self.yy:
	119	self.putx([Ann.WARN, ['Warning: Unexpected bytes in reply!']])
	120
	121	def handle_cmd_read_signature_byte_0x02(self, cmd, ret):
	122	# Signature byte 0x02: part number.
	123	self.part_number = ret[3]
	124	self.putx([Ann.RSB2, ['Part number: 0x%02x' % ret[3]]])
	125
	126	# Part name if known
	127	key = (self.part_fam_flash_size, self.part_number)
	128	if key in part:
	129	p = part[key]
	130	data = [Ann.DEV, ['Device: Atmel %s' % p]]
	131	self.put(self.ss_device, self.es_cmd, self.out_ann, data)
	132
	133	# Sanity check on reply.
	134	if ret[1] != 0x30 or ret[2] != self.xx or ret[0] != self.mm:
	135	self.putx([Ann.WARN, ['Warning: Unexpected bytes in reply!']])
	136
	137	self.xx, self.yy, self.zz, self.mm = 0, 0, 0, 0
	138
	139	def handle_cmd_chip_erase(self, cmd, ret):
	140	# Chip erase (erases both flash an EEPROM).
	141	# Upon successful chip erase, the lock bits will also be erased.
	142	# The only way to end a Chip Erase cycle is to release RESET#.
	143	self.putx([Ann.CE, ['Chip erase']])
	144
	145	# TODO: Check/handle RESET#.
	146
	147	# Sanity check on reply.
	148	bit = (ret[2] & (1 << 7)) >> 7
	149	if ret[1] != 0xac or bit != 1 or ret[3] != cmd[2]:
	150	self.putx([Ann.WARN, ['Warning: Unexpected bytes in reply!']])
	151
	152	def handle_cmd_read_fuse_bits(self, cmd, ret):
	153	# Read fuse bits.
	154	self.putx([Ann.RFB, ['Read fuse bits: 0x%02x' % ret[3]]])
	155
	156	# TODO: Decode fuse bits.
	157	# TODO: Sanity check on reply.
	158
	159	def handle_cmd_read_fuse_high_bits(self, cmd, ret):
	160	# Read fuse high bits.
	161	self.putx([Ann.RHFB, ['Read fuse high bits: 0x%02x' % ret[3]]])
	162
	163	# TODO: Decode fuse bits.
	164	# TODO: Sanity check on reply.
	165
	166	def handle_cmd_read_extended_fuse_bits(self, cmd, ret):
	167	# Read extended fuse bits.
	168	self.putx([Ann.REFB, ['Read extended fuse bits: 0x%02x' % ret[3]]])
	169
	170	# TODO: Decode fuse bits.
	171	# TODO: Sanity check on reply.
	172
	173	def handle_cmd_read_lock_bits(self, cmd, ret):
	174	# Read lock bits
	175	self.putx([Ann.RLB, ['Read lock bits: 0x%02x' % ret[3]]])
	176
	177	def handle_cmd_read_eeprom_memory(self, cmd, ret):
	178	# Read EEPROM Memory
	179	_addr = ((cmd[1] & 1) << 8) + cmd[2]
	180	self.putx([Ann.REEM, ['Read EEPROM Memory: [0x%03x]: 0x%02x' % (_addr, ret[3])]])
	181
	182	def handle_cmd_read_program_memory(self, cmd, ret):
	183	# Read Program Memory
	184	_HL = 'Low'
	185	_H = 'L'
	186	if cmd[0] & 0x08:
	187	_HL = 'High'
	188	_H = 'H'
	189	_addr = ((cmd[1] & 0x0f) << 8) + cmd[2]
	190	self.putx([Ann.RP, [
	191	'Read program memory %s: [0x%03x]: 0x%02x' % (_HL, _addr, ret[3]),
	192	'[%03x%s]:%02x' % (_addr, _H, ret[3]),
	193	'%02x' % ret[3]
	194	]])
	195
	196	def handle_cmd_load_program_memory_page(self, cmd, ret):
	197	# Load Program Memory Page
	198	_HL = 'Low'
	199	_H = 'L'
	200	if cmd[0] & 0x08:
	201	_HL = 'High'
	202	_H = 'H'
	203	_addr = cmd[2] & 0x1F
	204	self.putx([Ann.LPMP, [
	205	'Load program memory page %s: [0x%03x]: 0x%02x' % (_HL, _addr, cmd[3]),
	206	'[%03x%s]=%02x' % (_addr, _H, cmd[3]),
	207	'%02x' % cmd[3]
	208	]])
	209
	210	def handle_cmd_write_program_memory_page(self, cmd, ret):
	211	# Write Program Memory Page
	212	_addr = ((cmd[1] & 0x0F) << 3) + (cmd[2] << 5)
	213	self.putx([Ann.WP, ['Write program memory page: 0x%02x' % _addr]])
	214
	215	def handle_command(self, cmd, ret):
	216	if cmd[:2] == [0xac, 0x53]:
	217	self.handle_cmd_programming_enable(cmd, ret)
	218	elif cmd[0] == 0xac and (cmd[1] & (1 << 7)) == (1 << 7):
	219	self.handle_cmd_chip_erase(cmd, ret)
	220	elif cmd[:3] == [0x50, 0x00, 0x00]:
	221	self.handle_cmd_read_fuse_bits(cmd, ret)
	222	elif cmd[:3] == [0x58, 0x08, 0x00]:
	223	self.handle_cmd_read_fuse_high_bits(cmd, ret)
	224	elif cmd[:3] == [0x50, 0x08, 0x00]:
	225	self.handle_cmd_read_extended_fuse_bits(cmd, ret)
	226	elif cmd[0] == 0x30 and cmd[2] == 0x00:
	227	self.handle_cmd_read_signature_byte_0x00(cmd, ret)
	228	elif cmd[0] == 0x30 and cmd[2] == 0x01:
	229	self.handle_cmd_read_signature_byte_0x01(cmd, ret)
	230	elif cmd[0] == 0x30 and cmd[2] == 0x02:
	231	self.handle_cmd_read_signature_byte_0x02(cmd, ret)
	232	elif cmd[:2] == [0x58, 0x00]:
	233	self.handle_cmd_read_lock_bits(cmd,ret)
	234	elif cmd[0] == 0xa0 and (cmd[1] & (3 << 6)) == (0 << 6):
	235	self.handle_cmd_read_eeprom_memory(cmd, ret)
	236	elif (cmd[0] == 0x20 or cmd[0] == 0x28) and ((cmd[1] & 0xf0) == 0x00):
	237	self.handle_cmd_read_program_memory(cmd, ret)
	238	elif (cmd[0] == 0x40 or cmd[0] == 0x48) and ((cmd[1] & 0xf0) == 0x00):
	239	self.handle_cmd_load_program_memory_page(cmd, ret)
	240	elif (cmd[0] == 0x4C and ((cmd[1] & 0xf0) == 0x00)):
	241	self.handle_cmd_write_program_memory_page(cmd, ret)
	242	else:
	243	c = '%02x %02x %02x %02x' % tuple(cmd)
	244	r = '%02x %02x %02x %02x' % tuple(ret)
	245	self.putx([Ann.WARN, ['Unknown command: %s (reply: %s)!' % (c, r)]])
	246
	247	def decode(self, ss, es, data):
	248	ptype, mosi, miso = data
	249
	250	# For now, only use DATA and BITS packets.
	251	if ptype not in ('DATA', 'BITS'):
	252	return
	253
	254	# Store the individual bit values and ss/es numbers. The next packet
	255	# is guaranteed to be a 'DATA' packet belonging to this 'BITS' one.
	256	if ptype == 'BITS':
	257	self.miso_bits, self.mosi_bits = miso, mosi
	258	return
	259
	260	self.ss, self.es = ss, es
	261
	262	if len(self.mosi_bytes) == 0:
	263	self.ss_cmd = ss
	264
	265	# Append new bytes.
	266	self.mosi_bytes.append(mosi)
	267	self.miso_bytes.append(miso)
	268
	269	# All commands consist of 4 bytes.
	270	if len(self.mosi_bytes) < 4:
	271	return
	272
	273	self.es_cmd = es
	274
	275	self.handle_command(self.mosi_bytes, self.miso_bytes)
	276
	277	self.mosi_bytes = []
	278	self.miso_bytes = []