Jun 302017

This small thermal printer is very basic and uses 1980s style ESC/POS control codes (like most similar printers of this type that are used in shops for receipt printing). Sending UTF-8 text directly to it (such as any accented characters) doesn’t work well, as the accented characters have different codes (this printer can use a variety of old DOS code pages but defaults to 437).

Luckily Python has all these text conversion functions built in (you don’t even need to roll your own lookup tables!)

# # # convert UTF-8 to codepage for thermal printer # # # this is UTF-8 text with German characters # import pprint import serial # # USB converter device name for thermal printer # ttyname = 'COM2' text1 = [ 'Sie kam als Kind\nwohl am Sonntag an,\n', 'denn sie hieß,\nseit ich denken kann,\n', 'immer nur Sunday Girl.\n', 'Sie war nie Schuld,\nganz egal woran,\n', 'ihr hat nie etwas weh getan,\n', 'denn sie war Sunday Girl.\n\n', 'Kalt wie Eis und genau so süß\n', 'so war sie und auch manchmal\nganz schön mies.\n', 'Für sie war es ein Kinderspiel,\n', 'pech für den, dem sie gefiel.\n', ] # # convert output to list of bytes with codepage # using printers default codepage 437 # opt =[] for i in range(len(text1)): byt = str.encode(text1[i],'cp437') opt.append(byt) # # open the printer port and send data # s=serial.Serial(ttyname,19200) # # centre the title text and bold it # s.write(b'\x1ba1\x1bE1') s.write(b'Text conversion test\n\n') s.write(b'\x1ba0\x1bE0') # print the converted text for i in range(len(opt)): s.write(opt[i]) # # done, print complete message # s.write(b'\x1ba1\x1bE1') s.write(b'\n\nComplete...\n\n\n') s.write(b'\x1ba0\x1bE0')

Jun 222017

Python3 code is below…

also available at this Gitlab link


# control the Arduino RF22 pager TX # modified ON1ARF code # # 2017-06-23 Alex The Engineer # The Rat's Nest, Ipswich UK # # import serial import pprint import sys from colorconsole import terminal from colored import fg, bg, attr import readline # global colours res=attr('reset') # tty open now coded as a function # # colored module used here instead of colorconsole/screen object # just in case there isn't a global screen object available # def page(ttydev,capcode,function,repeats,message): # # create msg bytearray (NB: there should be more error # checking here # msg=(b'P ') msg+=(b'%07d' % capcode)+(b' ') msg+=(b'%01d' % function)+(b' ') msg+=(b'%01d' % repeats)+(b' ') msg+=(message)+(b'\r') print (fg(80),bg(0x12),'** opening tty:',ttydev+res) # serial port open with error checking this time try: ser = serial.Serial(ttydev, timeout=3) except serial.SerialException: print(res) sys.exit("** ERROR: cannot open tty\n\n") # if we got here everything is OK # RTS/DTR does not actually need to be flipped # as opening the tty does that anyway # which saves some time starting up the arduino comms # ser.setRTS(True) # ser.setRTS(False) # # get the lines from the buffer print (fg(0x0b),bg(0x15),'** tty open OK: >>check TX<<'+res) ibuf = ser.readlines() print (fg(202)) #pprint.pprint(ibuf) print (' ibuf[0] :',ibuf[0]) print (' ibuf[-1] :',ibuf[-1]) # check to see what came down comms line is expected if ibuf[0] != (b'RF22 init OK\r\n'): print(res) sys.exit("** ERROR: RF22 init error\n\n") if ibuf[-1] != (b'F <freqmhz> <freq100Hz>\r\n'): print(res) sys.exit("** ERROR: RF22 comms error\n\n") # if TX has correctly initialised now send message ser.write(msg) # get a line back from TTY, it should be exactly same as msg # but with a \n after it # if it hasn't something has gone wrong check=ser.readline() print(fg(0x50),'<< from tty:',fg(0x72),bg(0x08),check,res,fg(0x52)) if check != (msg+b'\n'): print(res) sys.exit("** ERROR: pager comms error\n\n") print (' ++ comms to pager TX OK ++') # get data returned over comms link # and now echo it with some pretty colours 🙂 colindex=0x70 while True: data=ser.readline() # only print it if a sending confirmation if data==(b'POCSAG SEND\r\n'): print (fg(0x30),'<< from tty:',fg(colindex),data) colindex += 1 if data==(b'F <freqmhz> <freq100Hz>\r\n'): break # all done, close tty print (fg(0x28),'** message sent correctly **\n') ser.close() def header(scr): scr = terminal.get_terminal(conEmu=False) scr.clear() scr.xterm256_set_fg_color(0x52) scr.xterm256_set_bk_color(0x08) scr.print_at(2,0,"rtn telecom : pagertest 1.00") scr.xterm256_set_bk_color(0) scr.gotoXY(2,3) scr.xterm256_set_fg_color(0x20) print('capcode:') scr.xterm256_set_bk_color(0x08) scr.xterm256_set_fg_color(0x78) scr.gotoXY(10,3) print(' ') scr.xterm256_set_bk_color(0) scr.gotoXY(20,3) scr.xterm256_set_fg_color(0x20) print('alert:') scr.xterm256_set_bk_color(0x08) scr.xterm256_set_fg_color(0x78) scr.gotoXY(26,3) print(' ') scr.xterm256_set_bk_color(0) scr.gotoXY(2,5) scr.xterm256_set_fg_color(0x20) print('message:') scr.xterm256_set_bk_color(0x08) scr.xterm256_set_fg_color(0x78) scr.gotoXY(10,5) print(' ') scr.xterm256_set_bk_color(0) scr.gotoXY(0,9) scr.xterm256_set_fg_color(0x28) # to be developed, input capcode def get_capcode(scr,default): pass # display capcode in input box def disp_capcode(scr,capcode): scr.xterm256_set_bk_color(0x08) scr.xterm256_set_fg_color(0x78) scr.gotoXY(10,3) print (str((b'%07d' % capcode),'utf-8')) scr.xterm256_set_bk_color(0) # display alert code in input box def disp_alert(scr,alert): scr.xterm256_set_bk_color(0x08) scr.xterm256_set_fg_color(0x78) scr.gotoXY(26,3) print (str((b'%01d' % alert),'utf-8')) scr.xterm256_set_bk_color(0) # display message in input box def disp_msg(scr,message): scr.xterm256_set_bk_color(0x08) scr.xterm256_set_fg_color(0x78) scr.gotoXY(10,5) print (str(message,'utf-8')) scr.xterm256_set_bk_color(0) scr.gotoXY(0,9) # # main code now starts here # # initialise the screen # # 2017-06-23: now accepts interactive input of message # # a blank line transmits the hardcoded message # # 'q' exits the code # while True: # refresh the header screen = terminal.get_terminal(conEmu=False) header(screen) # message now split into capcode, function (0-3), repeats # and 40 character bytearray # # hardcoded values # capcode = 20008 function = 2 repeats = 1 message = b'rtn: miauw naar de maan!<<<pagertest>>>' ttydev="/dev/ttyACM0" # display the capcode and alert that are currently hardcoded # but leave the msg box blank as it now accepts user input # disp_capcode(screen,capcode) disp_alert(screen,function) # # create a quick and dirty coloured prompt for the input # screen.gotoXY(2,7) screen.xterm256_set_fg_color(0x38) print('------>') screen.gotoXY(10,7) screen.xterm256_set_fg_color(0x68) # # this uses readline so has some basic editing functions # # anything over 40 character is clipped # ms1=input() if ms1 !='': message=ms1[0:40].encode('utf-8') if ms1 =='q': break # # display the msg in the top box and transmit it # disp_msg(screen,message) page(ttydev,capcode,function,repeats,message) # # terminate script and reset all the console colours # print (fg(0xc8),'\n++ Script completed sucessfully ++\n',res)
Jan 242017

These UHF portable radio sets are good value, [I am obtaining some for use by the janitorial and maintenance teams at work] but the supplied mains chargers aren’t the safest design – and like most similar chargers they also cook the accus if they are left on charge constantly which often happens when these sets are used by less technically minded endusers.

Update: Newer versions of this radio sold on Amazon are now supplied with a desk charger with a USB plug; it seems Baofeng have been monitoring the various comments from European users (and their modifications to the chargers) widely posted on blogs and social media (fair play to them!)

This is of course much safer and can also be used with any suitable USB power supply including cigarette lighter adapters for vehicles, but there are still a fair few units being sold with the mains powered desktop charger as well as many others in regular use worldwide.

You can also get better 6 unit chargers from HongKong which have a separate low voltage PSU (similar in size to a laptop charger) that connects to the desktop unit but in the meantime I investigated and modified one of the chargers I already have to make it slightly safer – a fiddly and awkward job due to the way this cheap charger is constructed.

ATTENTION: Don’t try this unless you are confident with working on mains voltage equipment!

Below are some pictures showing whats inside, a very simplified explanation of how this kind of charger works and why changing the cable is a good idea (I also used a better plug with a 5A fuse). The good news is that it all worked when I put the case back together (I definitely wasn’t going to attempt testing it with the live PCB exposed), and the output voltage at the terminals was correct (compared with that of an identical unit)

overview of SMPSU repair & operationoverview of SMPSU repair & operation

Dec 172016

code below

/*=========================================================================== * Serial Port Programming in C (Serial Port Write) * Non Cannonical mode * Program writes a character to the serial port at 19200 bps 8N1 format *--------------------------------------------------------------------------- * original Programmer : Rahul.S * Date : 21-December-2014 *============================================================================ * altered by : Alex the Engineer * rtn VFRmedia the Rat's nest * Ipswich GB * to work with x86 netbook connected to Sparkfun thermal printer * via USB-TTL serial converter * Date : 2016-05-29 * 2016-05-30 : code recompiled to ZX-SL91 * (old Tosh amd64 laptop with busted keyboard repurposed as mini * server * ---------------------------------------------------------------------------- * 2016-06-10 : sourcecode formatting cleaned up a bit *============================================================================== /*-------------------------------------------------------------*/ /* termios structure - /usr/include/asm-generic/termbits.h */ /* use "man termios" to get more info about termios structure */ /*-------------------------------------------------------------*/ #include <stdio.h> #include <fcntl.h> /* File Control Definitions */ #include <string.h> /* strings */ #include <termios.h> /* POSIX Terminal Control Definitions */ #include <unistd.h> /* UNIX Standard Definitions */ #include <errno.h> /* ERROR Number Definitions */ /* global vars - probably shouldn't be hardcoded like this */ /* and some should be #defines to save memory */ /* but better than sticking them into the sourcecode */ int bytes_written = 0; /* Buffer containing characters to write into port */ char *write_buffer = "\x1b@\n\n\n" "\x1b\x0ertn\n" "telecommunicatie\x1b\x14\n" "printertest ZX-SL91\n" "\nAchtung! Achtung!\n" "The Goose is Loose!\n" "\x1d\x48\x03\n"; char *msg2= "\x1b@" "rtn :miauw naar de maan!\n\n\n\n\n"; char *barcode128n= "\x1d\x6bI"; char *item1= "2815 doedelzak"; char *item2= "9502 asbak "; char *item3= "7281 snakeoil "; char *lin_adv= "\n"; int main(void) { int fd; /*File Descriptor*/ printf("\n +----------------------------------+"); printf("\n | Serial Port Write |"); printf("\n +----------------------------------+"); /*------------------------------- Opening the Serial Port ------*/ /* Change /dev/ttyUSB0 to the one corresponding to your system */ fd = open("/dev/ttyUSB0",O_RDWR | O_NOCTTY | O_NDELAY); /* ttyUSB0 is the FT232 based USB2SERIAL Converter */ /* O_RDWR Read/Write access to serial port */ /* O_NOCTTY - No terminal will control the process */ /* O_NDELAY -Non Blocking Mode,Does not care about- */ /* -the status of DCD line,Open() returns immediatly */ if(fd == -1) { /* Error Checking */ perror("\n Error! in Opening ttyUSB0 "); return -1; } else perror("\n ttyUSB0 Opened Successfully "); /* set tty attrs 19200 8N1 */ struct termios SerialPortSettings; tcgetattr(fd, &SerialPortSettings); cfsetispeed(&SerialPortSettings,B19200); cfsetospeed(&SerialPortSettings,B19200); SerialPortSettings.c_cflag &= ~PARENB; SerialPortSettings.c_cflag &= ~CSTOPB; SerialPortSettings.c_cflag &= ~CSIZE; SerialPortSettings.c_cflag |= CS8; SerialPortSettings.c_cflag &= ~CRTSCTS; SerialPortSettings.c_cflag |= CREAD | CLOCAL; SerialPortSettings.c_iflag &= ~(IXON | IXOFF | IXANY); SerialPortSettings.c_iflag &= ~(ICANON | ECHO | ECHOE | ISIG); SerialPortSettings.c_oflag &= ~OPOST;/*No Output Processing*/ /* Set the attributes to the termios structure*/ if((tcsetattr(fd,TCSANOW,&SerialPortSettings)) != 0) { perror ("\n ERROR! in set attrs"); return -1; } else printf("\n ttyUSB0 set to 19200-8N1\n"); bytes_written = str_send(fd,write_buffer); printf("\n Sending these 3 barcode:\n%s\n%s\n%s\n",item1,item2,item3); bytes_written += bc128_send(fd,item1); bytes_written += bc128_send(fd,item2); bytes_written += bc128_send(fd,item3); bytes_written += str_send(fd,msg2); printf("\n %d Bytes written to ttyUSB0", bytes_written); printf("\n +----------------------------------+\n\n"); close(fd);/* Close the Serial port */ } /* str_send : write string of bytes to the serial port */ /* specified by fd */ /* returns number of bytes written */ int str_send (int fd, char *msg) { return write(fd,msg,strlen(msg)); } /* bc128_send : send code128 barcode from string */ /* create code 128 barcode - Achtung! uses fixed length sequence */ /* with hardcoded length of 14 (0x0e) sent to printer */ /* which must be specified as a string even though it is only 1 byte */ /* or wrong data is sent down the line */ /* and the barcodes do not print */ int bc128_send (int fd, char *barcode) { int bcount = 0; bcount += write(fd,barcode128n,3); bcount += write(fd,"\x0e",1); bcount += write(fd,barcode,14); return bcount; }
Aug 132016

The CCTV at work was upgraded;  I got to recover the old DVR and have repurposed it alongside a cheap camera mounted at low level to watch cats and other creatures in my garden. It is better than normal British TV, like having your own personal nature channel 🙂

all creatures great and small :)

The statue of the Blessed Virgin Mary also reminds me to take care with the metal box as its a 230V to 12V psu where I mislaid the case screws, there is 230V mains on terminals inside it)

catcam monitor

This cat is the ringleader, but he shares the space with around 5 others and seems to even encourage them to visit my garden…


One bonus of this arrangement is if I see a cat I can sometimes then photograph it with a better camera (the kitties are often surprised that I seem to know where they are 🙂 )

moar kittehs


Kätzin, interrupted....

Interestingly they seem to behave better since the CCTV was installed; they do not fight each other and make noise with miauwing at night nor foul this side of the garden.

It is not just cats either I see on the camera…

Hedgehog seen on the catcam!

Apologies for poor quality but that is a hedgehog. Apparently these are getting rare in some bits of England so I reported the sighting to Suffolk Wildlife Trust who put it on their map. A lot of folk seem to feed hedgehogs with cat food, I wonder if they are actually following the cats around (they are too big and well protected for lazy town cats to bother with them as prey)…