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Python, HEX, Serial, and Print

Using Python 3, I need to write data 0x00 - 0xff through serial one byte at a time and also want to print on the screen the current byte in Hex where it is in the loop. Now that I've been working on this, it seems like I can just make a simple for loop counting from 0 - 255 and send that.
But, for learning purposes is the way I declared this variable correct?
# Characters to test, all 255 chars
mytest = { '\00', '\01', '\02', '\03', '\04', '\05', '\06', '\07', '\08', '\09', '\0a', '\0b', '\0c', '\0d', '\0e', '\0f', \
'\10', '\11', '\12', '\13', '\14', '\15', '\16', '\17', '\18', '\19', '\1a', '\1b', '\1c', '\1d', '\1e', '\1f', \
'\20', '\21', '\22', '\23', '\24', '\25', '\26', '\27', '\28', '\29', '\2a', '\2b', '\2c', '\2d', '\2e', '\2f', \
'\30', '\31', '\32', '\33', '\34', '\35', '\36', '\37', '\38', '\39', '\3a', '\3b', '\3c', '\3d', '\3e', '\3f', \
'\40', '\41', '\42', '\43', '\44', '\45', '\46', '\47', '\48', '\49', '\4a', '\4b', '\4c', '\4d', '\4e', '\4f', \
'\50', '\51', '\52', '\53', '\54', '\55', '\56', '\57', '\58', '\59', '\5a', '\5b', '\5c', '\5d', '\5e', '\5f', \
'\60', '\61', '\62', '\63', '\64', '\65', '\66', '\67', '\68', '\69', '\6a', '\6b', '\6c', '\6d', '\6e', '\6f', \
'\70', '\71', '\72', '\73', '\74', '\75', '\76', '\77', '\78', '\79', '\7a', '\7b', '\7c', '\7d', '\7e', '\7f', \
'\80', '\81', '\82', '\83', '\84', '\85', '\86', '\87', '\88', '\89', '\8a', '\8b', '\8c', '\8d', '\8e', '\8f', \
'\90', '\91', '\92', '\93', '\94', '\95', '\96', '\97', '\98', '\99', '\9a', '\9b', '\9c', '\9d', '\9e', '\9f', \
'\a0', '\a1', '\a2', '\a3', '\a4', '\a5', '\a6', '\a7', '\a8', '\a9', '\aa', '\ab', '\ac', '\ad', '\ae', '\af', \
'\b0', '\b1', '\b2', '\b3', '\b4', '\b5', '\b6', '\b7', '\b8', '\b9', '\ba', '\bb', '\bc', '\bd', '\be', '\bf', \
'\c0', '\c1', '\c2', '\c3', '\c4', '\c5', '\c6', '\c7', '\c8', '\c9', '\ca', '\cb', '\cc', '\cd', '\ce', '\cf', \
'\d0', '\d1', '\d2', '\d3', '\d4', '\d5', '\d6', '\d7', '\d8', '\d9', '\da', '\db', '\dc', '\dd', '\de', '\df', \
'\e0', '\e1', '\e2', '\e3', '\e4', '\e5', '\e6', '\e7', '\e8', '\e9', '\ea', '\eb', '\ec', '\1e', '\ee', '\ef', \
'\f0', '\f1', '\f2', '\f3', '\f4', '\f5', '\f6', '\f7', '\f8', '\f9', '\fa', '\fb', '\fc', '\fd', '\fe', '\ff' }
for c in mytest:
print (" ".join(hex(ord(n)) for n in c))
serial.write(c) # Let's pretend this sends the same to the serial port I defined somewhere.
Reading posts here, I have come up with the above to print the hex to screen. Which works, sort of.. when I put in one char at a time to test with. However instead of 0x00 it is printing 0x0 I am expecting two 00's well, three I guess 0x00. AND when I run it in the loop, I get all sorts of unexpected output. lol
Test output using single bytes..
0x0 0x1 0x2
Output when running in the for loop...
0x5c 0x38 0x39
0xc
0x8
0x7 0x30
0x5c 0x63 0x65
0x5c 0x39 0x36
0x5c 0x38 0x35
0x5c 0x64 0x36
0x5c 0x65 0x35
0x5c 0x38 0x37
0xc 0x30
0x5c 0x63 0x61
0x4 0x39
0x5c 0x64 0x64
0x0 0x65
0x1e
0x5c 0x63 0x31
0x24
0x4 0x61
0x8 0x37
0x7 0x37
0x8 0x38
0x1b
0x4 0x38
0x26
0x4 0x66
0x2e
0x5c 0x38 0x64
0x5c 0x39 0x64
0x5c 0x64 0x38
0x0
0x2 0x63
0x5c 0x39 0x61
0x27
0x5 0x65
0x3 0x64
0x3
0x15
0x2 0x39
0x19
0x5 0x63
0x5c 0x64 0x35
0x7 0x39
0x8 0x66
0xc 0x31
0x5c 0x64 0x63
0x5
0x3 0x66
0x5c 0x63 0x62
0x5c 0x65 0x63
0x5c 0x63 0x38
0x2a
0x1d
0x5c 0x38 0x63
0x8 0x63
0x5c 0x65 0x30
0x2 0x61
0x1 0x66
0xc 0x64
0x5c 0x65 0x62
0x5c 0x64 0x31
0x0 0x64
0xe
0x5 0x64
0x5c 0x65 0x37
0x5c 0x38 0x38
0x5c 0x65 0x39
0x5c 0x63 0x36
0xc 0x36
0x7 0x36
0x5c 0x65 0x31
0xb
0x2f
0x8 0x62
0x1
0x31
0x5c 0x38 0x61
0x1 0x39
0x2 0x38
0x6 0x38
0x1 0x62
0x3b
0x5c 0x63 0x33
0x5c 0x64 0x65
0x6 0x63
0x2b
0x5 0x66
0x8 0x64
0x5c 0x65 0x38
0x5c 0x64 0x62
0x6 0x64
0x5c 0x38 0x34
0x6 0x62
0x5c 0x39 0x30
0x6 0x61
0x16
0x1c
0x4 0x64
0xc 0x37
0x5c 0x64 0x66
0x5c 0x39 0x39
0x5c 0x63 0x39
0x8 0x32
0x3 0x65
0x11
0x28
0x5c 0x38 0x62
0x0 0x66
0xd
0x5 0x62
0x8 0x34
0x33
0x7 0x38
0x7 0x66
0x5c 0x39 0x32
0x4 0x63
0x2 0x66
0x1 0x38
0x7 0x31
0x5c 0x64 0x37
0x36
0x8 0x35
0x1 0x64
0x5c 0x39 0x31
0x5c 0x65 0x66
0x0 0x61
0x2 0x62
0x22
0x5c 0x64 0x32
0x0 0x38
0x25
0x5c 0x65 0x33
0x32
0xf
0x8 0x61
0x2 0x64
0x5c 0x63 0x34
0xc 0x38
0x7 0x61
0x8 0x36
0x2 0x65
0x1f
0x7 0x35
0x0 0x63
0xc 0x65
0x5c 0x63 0x30
0x5c 0x64 0x61
0x3 0x62
0x7 0x62
0x7 0x65
0x4 0x62
0x8 0x65
0x7 0x63
0x6
0x5c 0x39 0x66
0x5c 0x64 0x39
0x2
0xa
0x3 0x39
0x5 0x39
0x5c 0x64 0x30
0x5 0x38
0x3 0x63
0x3c
0x5c 0x63 0x37
0x7 0x64
0x9
0xc 0x63
0x3e
0x0 0x62
0x17
0xc 0x61
0x5c 0x63 0x35
0x5c 0x38 0x66
0x38
0x5c 0x64 0x33
0x5c 0x63 0x66
0x5c 0x38 0x30
0x5c 0x63 0x64
0x5c 0x65 0x65
0xc 0x34
0x5c 0x39 0x37
0x5c 0x63 0x32
0x8 0x30
0x1 0x65
0xc 0x32
0xc 0x35
0x6 0x39
0x5c 0x38 0x32
0x5c 0x65 0x61
0x3 0x38
0x5c 0x64 0x34
0x5c 0x65 0x32
0x1 0x61
0x5c 0x63 0x63
0x4 0x65
0x13
0x23
0x2c
0x3a
0x6 0x65
0x3f
0x8 0x39
0x34
0x39
0x5c 0x39 0x65
0x7
0x12
0x35
0xc 0x33
0x8 0x31
0x6 0x66
0x3 0x61
0x5c 0x38 0x36
0x18
0x0 0x39
0x37
0xc 0x39
0x5c 0x65 0x36
0x5c 0x39 0x63
0x3d
0x7 0x33
0x5c 0x38 0x33
0x5c 0x38 0x65
0x5c 0x39 0x34
0x21
0x5c 0x39 0x62
0x14
0x1a
0x7 0x34
0x5c 0x39 0x33
0x5c 0x65 0x34
0x4
0x2d
0x10
0x29
0x5c 0x39 0x35
0x1 0x63
0x20
0xc 0x62
0x7 0x32
0x5 0x61
0x8 0x33
0xc 0x66
0x30
0x5c 0x39 0x38
0x5c 0x38 0x31
Let's say the device on the other end of the serial connection is looking for
"0x01, 0x02, 0x03, 0xbb"
Questions:
Is there a difference between 0x0 and 0x00 when sending over serial?
I think it is just a representation of the same information. Therefore, 0x00 IS the same as 0x0, or 0x01 and 0x1.
What is wrong with my variable declaration to make the garbage come out when I print in the loop?
I think something like this will accomplish what I want, assuming 0x01 and 0x1 are the same:
for x in range(256)
print (" ".join(hex(ord(n)) for n in x))
serial.write(x)
Thank you.

Well, for one you need to use [ and ] in the variable declaration. In Python, { makes a set, which is unordered. [ makes a list, which is ordered.
Then for the actual content, you need to use \x00, not just \00. So your declaration should be
mytest = [ '\x00', '\x01', '\x02', '\x03', '\x04', '\x05', '\x06', '\x07', '\x08', '\x09', '\x0a', '\x0b', '\x0c', '\x0d', '\x0e', '\x0f', \
'\x10', '\x11', '\x12', '\x13', '\x14', '\x15', '\x16', '\x17', '\x18', '\x19', '\x1a', '\x1b', '\x1c', '\x1d', '\x1e', '\x1f', \
'\x20', '\x21', '\x22', '\x23', '\x24', '\x25', '\x26', '\x27', '\x28', '\x29', '\x2a', '\x2b', '\x2c', '\x2d', '\x2e', '\x2f', \
'\x30', '\x31', '\x32', '\x33', '\x34', '\x35', '\x36', '\x37', '\x38', '\x39', '\x3a', '\x3b', '\x3c', '\x3d', '\x3e', '\x3f', \
'\x40', '\x41', '\x42', '\x43', '\x44', '\x45', '\x46', '\x47', '\x48', '\x49', '\x4a', '\x4b', '\x4c', '\x4d', '\x4e', '\x4f', \
'\x50', '\x51', '\x52', '\x53', '\x54', '\x55', '\x56', '\x57', '\x58', '\x59', '\x5a', '\x5b', '\x5c', '\x5d', '\x5e', '\x5f', \
'\x60', '\x61', '\x62', '\x63', '\x64', '\x65', '\x66', '\x67', '\x68', '\x69', '\x6a', '\x6b', '\x6c', '\x6d', '\x6e', '\x6f', \
'\x70', '\x71', '\x72', '\x73', '\x74', '\x75', '\x76', '\x77', '\x78', '\x79', '\x7a', '\x7b', '\x7c', '\x7d', '\x7e', '\x7f', \
'\x80', '\x81', '\x82', '\x83', '\x84', '\x85', '\x86', '\x87', '\x88', '\x89', '\x8a', '\x8b', '\x8c', '\x8d', '\x8e', '\x8f', \
'\x90', '\x91', '\x92', '\x93', '\x94', '\x95', '\x96', '\x97', '\x98', '\x99', '\x9a', '\x9b', '\x9c', '\x9d', '\x9e', '\x9f', \
'\xa0', '\xa1', '\xa2', '\xa3', '\xa4', '\xa5', '\xa6', '\xa7', '\xa8', '\xa9', '\xaa', '\xab', '\xac', '\xad', '\xae', '\xaf', \
'\xb0', '\xb1', '\xb2', '\xb3', '\xb4', '\xb5', '\xb6', '\xb7', '\xb8', '\xb9', '\xba', '\xbb', '\xbc', '\xbd', '\xbe', '\xbf', \
'\xc0', '\xc1', '\xc2', '\xc3', '\xc4', '\xc5', '\xc6', '\xc7', '\xc8', '\xc9', '\xca', '\xcb', '\xcc', '\xcd', '\xce', '\xcf', \
'\xd0', '\xd1', '\xd2', '\xd3', '\xd4', '\xd5', '\xd6', '\xd7', '\xd8', '\xd9', '\xda', '\xdb', '\xdc', '\xdd', '\xde', '\xdf', \
'\xe0', '\xe1', '\xe2', '\xe3', '\xe4', '\xe5', '\xe6', '\xe7', '\xe8', '\xe9', '\xea', '\xeb', '\xec', '\x1e', '\xee', '\xef', \
'\xf0', '\xf1', '\xf2', '\xf3', '\xf4', '\xf5', '\xf6', '\xf7', '\xf8', '\xf9', '\xfa', '\xfb', '\xfc', '\xfd', '\xfe', '\xff' ]
I'm not sure what the intention was with the line
print (" ".join(hex(ord(n)) for n in c))
If there is only one character in the string c, which there is, you can just do
print(hex(ord(c)))
The code you had looks like it was intended to print every character as hex in a big single string. That's why it had the for n in x.
That's also why the output you were getting before looked so wrong. Notice, on all the lines with multiple value, the first part was 0x5c, which is the ASCII code for \. So it was printing out the hex for \, a, b.
In your simplified loop, it would be as simple as
for x in range(256):
print (hex(x))
serial.write(x)
And as for the equivalence of 0x00 and 0x0, they are the same. The hex function in Python just returns a string that has the number in that notation. They are the same just like how the number 042 is the same as 42 in decimal. Anything you send to the serial won't even look like that. It will just be a number. But depending on the whatever serial library you are using, it probably wants a number not a string like c currently is. So you need to do serial.write(ord(c)) if you want to continue storing data as characters like that.
In fact, in Python you can have numeric literals directly written as hex. So you could say x = 0x32 just fine, which would be converted to 52 when the program is run. Or your whole list could be expressed like
mytest = [0x00, 0x01, 0x02,
etc. Then you wouldn't need any ord at all since everything would already be a number.

Optimize byte array escaping performance python

I need to perform custom escaping over a byte array in python. However, during escaping python converts bytes to integers, making performance optimization very difficult. How can I speed up my escaping function?
ESCAPE_DICT={
0x00: [0x5C,0x7A], # null -> \z 0x5c 0x7a
0x22: [0x5C,0x71], # " -> \q 0x5c 0x71
0x3B: [0x5C,0x73], # ; -> \s 0x5c 0x73
0x5C: [0x5C,0x5C], # \ -> \\ 0x5c 0x5c
0x0A: [0x5C,0x6E], # line-feed -> \n 0x5c 0x6e
0x0C: [0x5C,0x66], # form-feed -> \f 0x5c 0x66
0x0D: [0x5C,0x63], # carr-return -> \c 0x5c 0x63
}
def escape(string: bytes):
str_len=string.__len__()
escaped_list=[]
for i in range(0,str_len):
curr_byte=string[i]
escape = ESCAPE_DICT.get(curr_byte)
if escape is None:
# Don't escape current byte
escaped_list.append(curr_byte)
else:
# Escape current byte
escaped_list.extend(escape)
return bytes(escaped_array)

import re
ESCAPE_DICT = {
b'\x00': rb'\z', # null
b'"': rb'\q',
b';': rb'\s',
b'\\': rb'\\',
b'\n': rb'\n', # linefeed
b'\f': rb'\f', # formfeed
b'\r': rb'\c', # carriage return
}
ESCAPE_CLASS = '[' + ''.join(r'\x' + e.hex() for e in ESCAPE_DICT) + ']'
ESCAPE_REGEX = re.compile(ESCAPE_CLASS.encode())
def escape(string: bytes) -> bytes:
return re.sub(ESCAPE_REGEX, lambda m: ESCAPE_DICT[m.group(0)], string)
x = b'"abc\ndef\rpqr\x00stu\\xyz"'
y = escape(x)
from pprint import pprint
pprint(ESCAPE_CLASS)
pprint(ESCAPE_REGEX)
pprint(x)
pprint(y)
# =>
# '[\\x00\\x22\\x3b\\x5c\\x0a\\x0c\\x0d]'
# re.compile(b'[\\x00\\x22\\x3b\\x5c\\x0a\\x0c\\x0d]')
# b'"abc\ndef\rpqr\x00stu\\xyz"'
# b'\\qabc\\ndef\\cpqr\\zstu\\\\xyz\\q'
You can read the rb prefix as “raw bytes”.
Your escapes are a bit strange, though. E.g., the carriage return is normally \r, not \c, and \s normally stands for generic whitespace.

How to create EddyStone Beacon using BlueZ and Python?

I'm working on BLE(BlueTooth Low Energy) on an Embedded Linux board. We use BlueZ and Python. I need to create EddyStone Beacon. I found there is a way to create iBeacon: https://scribles.net/creating-ibeacon-using-bluez-example-code-on-raspberry-pi/. I tried it. It worked.
But we need to create EddyStone Beacon. So I use the Beacon data format from here(https://ukbaz.github.io/howto/beacon_scan_cmd_line.html) to create the manufacturer data.
But my code doesn't work. What is wrong with my code? Here is my code:
def __init__(self, bus, index):
eddystone_id = 0xAAFE
beacon_type = [0x14, 0x16] # Length = 0x14, EddyStone type = 0x16
uuid = [0xAA, 0xFE] # EddyStone UUID = 0xAAFE
frame_type = [0x10] # Frame Type = 0x10
power = [0x00] # Power = 0x00
prefix = [0x02] # URL scheme = 0x02 (http://)
url = [0x73, 0x61, 0x6D, 0x70, 0x6C, 0x65, 0x77, 0x65, 0x62, 0x73, 0x69, 0x74, 0x65, 0x07]
Advertisement.__init__(self, bus, index, 'peripheral')
self.add_manufacturer_data(eddystone_id, beacon_type + uuid + frame_type + power + prefix + url)
However, if I use this command, the EddyStone Beacon is created. I can see it shows EddyStone Beacon in nRF mobile app:
sudo hcitool -i hci0 cmd 0x08 0x0008 1c 02 01 06 03 03 aa fe 14 16 aa fe 10 00 02 73 61 6d 70 6c 65 77 65 62 73 69 74 65 07 00 00 00
As you can see, the data I put in the add_manufacturer_data() function is the same as the data in the command. But why the Python code doesn't work?

iBeacon uses manufacturer_data while Eddystone beacons use service_data so I would expect your code to look more like this:
def __init__(self, bus, index):
Advertisement.__init__(self, bus, index, 'broadcast')
self.add_service_uuid('FEAA')
frame_type = [0x10] # Eddystone frame Type = 0x10
power = [0x00] # Beacon broadcast power = 0x00
prefix = [0x02] # URL scheme = 0x02 (http://)
url = [0x73, 0x61, 0x6D, 0x70, 0x6C, 0x65, 0x77, 0x65, 0x62, 0x73, 0x69, 0x74, 0x65, 0x07]
eddystone_data = frame_type + power + prefix + url
self.add_service_data('FEAA', eddystone_data)
As a side note, hcitool is one of the tools that has been deprecated by the BlueZ developers. The currently supported way to create the Eddystone beacon from the command line would be with bluetoothctl. The sequence of commands would be:
bluetoothctl
menu advertise
uuids 0xFEAA
service 0xFEAA 0x10 0x00 0x02 0x73 0x61 0x6D 0x70 0x6C 0x65 0x77 0x65 0x62 0x73 0x69 0x74 0x65 0x07
back
advertise broadcast
discoverable on
I changed the advertisement type from peripheral to broadcast because typically people don't want beacons to be connectable, but it depends on your application.

nrf24l01 communication raspberry pi not able to connect

I am new to Stackoverflow. I have searched for answer, but didn't find anything.
I have two Raspberry Pi 2B+, each with nRF24l01 connected. I found few libraries to make this connect, only one give any results, but not connections. This one: Github BLavery
I write script to send and to recv:
send.py:
import RPi.GPIO as GPIO
from lib_nrf24 import NRF24
import time
import spidev
GPIO.setmode(GPIO.BCM)
pipes = [[0xe7, 0xe7, 0xe7, 0xe7, 0xe7], [0xc2, 0xc2, 0xc2, 0xc2, 0xc2]]
radio = NRF24(GPIO, spidev.SpiDev())
radio.begin(0, 17)
radio.setPayloadSize(32)
radio.setChannel(0x60)
radio.setDataRate(NRF24.BR_2MBPS)
radio.setPALevel(NRF24.PA_MIN)
radio.setAutoAck(True)
radio.enableDynamicPayloads()
radio.enableAckPayload()
radio.openWritingPipe(pipes[1])
radio.printDetails()
while True:
message = list("Hello World")
radio.write(message)
print("We sent the message of {}".format(message))
# Check if it returned a ackPL
if radio.isAckPayloadAvailable():
returnedPL = []
radio.read(returnedPL, radio.getDynamicPayloadSize())
print("Our returned payload was {}".format(returnedPL))
else:
print("No payload received")
time.sleep(1)
recv.py:
import RPi.GPIO as GPIO
from lib_nrf24 import NRF24
import time
import spidev
GPIO.setmode(GPIO.BCM)
pipes = [[0xe7, 0xe7, 0xe7, 0xe7, 0xe7], [0xc2, 0xc2, 0xc2, 0xc2, 0xc2]]
radio = NRF24(GPIO, spidev.SpiDev())
radio.begin(0, 17)
radio.setPayloadSize(32)
radio.setChannel(0x60)
radio.setDataRate(NRF24.BR_2MBPS)
radio.setPAlevel(NRF24.PA_MIN)
radio.setAutoAck(True)
radio.enableDynamicPayloads()
radio.enableAckPayload()
radio.openReadingPipe(1, pipes[1])
radio.printDetails()
radio.startListening()
while True:
ackPL = [1]
while not radio.available (0):
time.sleep(1/100)
receivedMessage = []
radio.read(receivedMessage, radio.getDynamicPayloadSize())
print("Received: {}".format(receivedMessage))
print("Translating the receivedMessage into unicode characters...")
string = ""
for n in receivedMessage:
# Decode into standard i=unicode set
if (n >=32 and n <= 126):
string += chr(n)
print(string)
radio.writeAckPayload(1, ackPL, len(ackPL))
print("Loaded payload reply of {}".format(ackPL))
Everything seems to be alright, below are code returned by both scripts:
send:
STATUS = 0x03 RX_DR=0 TX_DS=0 MAX_RT=0 RX_P_NO=1 TX_FULL=1
RX_ADDR_P0-1 =
0xf8f8f8f8f8 0xf8f8f8f8f8
RX_ADDR_P2-5 =
0xf8
0xf9
0xf9
0xf9
TX_ADDR =
0xf8f8f8f8f8
RX_PW_P0-6 =
0x0c
0x00
0x00
0x00
0x00
0x00
EN_AA =
0x0f
EN_RXADDR =
0x00
RF_CH =
0x1c
RF_SETUP =
0x00
CONFIG =
0x03
DYNPD/FEATURE =
0x03
0x01
Data Rate = 1MBPS
Model = nRF24L01
CRC Length = Disabled
PA Power = PA_MIN
We sent the message of ['H', 'e', 'l', 'l', 'o', ' ', 'W', 'o', 'r', 'l', 'd']
No payload received
recv.py:
STATUS = 0x03 RX_DR=0 TX_DS=0 MAX_RT=0 RX_P_NO=1 TX_FULL=1
RX_ADDR_P0-1 =
0xf8f8f8f8f8 0xf8f8f8f8f8
RX_ADDR_P2-5 =
0xf8
0xf9
0xf9
0xf9
TX_ADDR =
0xf8f8f8f8f8
RX_PW_P0-6 =
0x0c
0x0c
0x00
0x00
0x00
0x00
EN_AA =
0x0f
EN_RXADDR =
0x00
RF_CH =
0x1c
RF_SETUP =
0x00
CONFIG =
0x03
DYNPD/FEATURE =
0x03
0x01
Data Rate = 1MBPS
Model = nRF24L01
CRC Length = Disabled
PA Power = PA_MIN
Received: []
Translating the receivedMessage into unicode characters...
Loaded payload reply of [1]
I don't really understand why it won't connect one to other,
Both have the same wiring:
nRF24L01-Raspberry Pi (Pin#)
GND - GND (6)
VCC - 3,3V (1)
CE - GPIO17 (11)
CSN - GPIO08(24)
SCK - GPIO11 (23)
MOSI - GPIO10 (19)
MISO - GPIO25 (22)
IRQ - unconnected
I need to send information from one RPi to second to control engine via PWM.
Can i ask for help

how to return [0x01, 0xFF,.....] as string ''01 FF ....' in python

I'm confused about this. how to print hexadecimal bytes:
[0x05, 0x06, 0x40, 0xFD, 0x05]
as this in the console:
05 06 40 FD 05
And how would I use this in a to_string function:
def to_string(bytes):
cmd = '%02X'.join(chr(b) for b in self.bytes) #does not work obviously
return cmd
print to_string([0x05, 0x06, 0x40, 0xFD, 0x05])
I thought I could generalize from your answer.

Use the %02X string formatter:
>>> print '%02X' % 0x05
05
>>> for i in [0x05, 0x06, 0x40, 0xFD, 0x05]:
... print '%02X' % i,
...
05 06 40 FD 05
or to make it one string:
>>> ' '.join(['%02X' % i for i in [0x05, 0x06, 0x40, 0xFD, 0x05]])
'05 06 40 FD 05'

Martijn's answer is the right answer, but here are some related functions you may not be familiar with.
With the python format string operator:
>>> for i in [0x05, 0x06, 0x40, 0xFD, 0x05]:
... print "{:02X}".format(i),
...
05 06 40 FD 05
If you actually had the data as bytestrings you could use binascii.hexlify to do the same.
>>> import binascii
>>> data = ["\x05", "\x06", "\x40", "\xFD", "\x05"]
>>> for d in data:
... print binascii.hexlify(d),
...
05 06 40 fd 05
You could also use the builtin hex() with your existing data if you don't mind the data not being padded.
>>> data = [0x05, 0x06, 0x40, 0xFD, 0x05]
>>> for i in data:
... print hex(i),
...
0x5 0x6 0x40 0xfd 0x5
>>>
>>>
>>> # Or use the slice operator to cut off the initial "0x"
>>> for i in data:
... print hex(i)[2:],
...
5 6 40 fd 5