Arduino MKR and M5Stack Printing on Portable Receipt Printer

Print pictures from Flash on a portable USB thermal printer. The printer and the MKR and M5Stack boards are running from their own batteries.

M5Stack Core + USB host module

This option is a nicely packaged ESP32 with battery and display. The optional M5Stack USB module provides the USB host interface for the printer. The USB module is based on the MAX3421E USB chip which is supported by the USB Host Shield 2.0 library.

Hardware

• M5Stack core (ESP32, battery, display, etc.) https://m5stack.com/collections/m5-core/products/grey-development-core
• M5Stack USB host module (MAX3421E) https://m5stack.com/collections/m5-module/products/usb-module
• USB cable for printer (black cable in picture)
• USB thermal receipt printer, 58mm wide, battery powered

Libraries

• USB Host Shield 2.0 https://github.com/felis/USB_Host_Shield_2.0
• USB Printer driver https://github.com/gdsports/USBPrinter_uhs2
• ESC POS library https://github.com/gdsports/ESC_POS_Printer

Arduino MKR board

Hardware

• Arduino MKR WiFi 1010 (SAMD21)
• Lithium battery
• USB OTG to host cable (red cable in picture)
• USB cable for printer (black cable in picture)
• USB thermal receipt printer, 58mm wide, battery powered

Libraries

• USB Host Library for SAMD https://github.com/gdsports/USB_Host_Library_SAMD
• USB Printer driver https://github.com/gdsports/USBPrinter_uhls
• ESC POS library https://github.com/gdsports/ESC_POS_Printer

The MKR board is powered by the battery shown. The printer is powered by its internal battery so the battery in the picture is not powering the printer.

This example program does not use the WiFi network so a MKR Zero should also work.

Portable receipt printer

The printer has two identical mini USB sockets. Be sure use the one labelled USB. The one labelled COM is an RS-232 port. The voltage is not compatible with USB and may damage the MKR or M5Stack board.

Links to shopping websites tend die so to find a similar printer, try the search term "portable thermal receipt printer" on your favorite shopping website. Unfortunately, it is not possible to tell if a printer is compatible with the ESC POS library so some changes may be necessary. Different printers implement different subsets of the ESC POS commands.

Convert picture to include file

mkpic.sh converts any image file supported by ImageMagick convert to a C include file. The image is resized to fit on a 384 dot wide printer. Colors are converted to dithered black and white dots. To preview the result, view output file bitmap.png. The other output file is the image name with ".h" appended.

$ ./mkpic.sh wave.png

bitmap.png is a black and white version of the wave.png file.

wave.png.h is a C include file with the black and white image processed for printing using the ESC * command. The Python program bitmapband.py converts bitmap.png to a C include file transposing rows and columns as needed.

Example output

#define bitmap_width   384
#define bitmap_height  258
#define bitmap_density 2

const uint8_t bitmap_data[] PROGMEM = {
0, 0, 0, 72, 16, 36, 2, 66, 0, 16, 0, 72, 65, ...
...
};

If the result is too light or dark, use a paint program such as PhotoShop or GIMP to adjust the image before running mkpic.sh.

Arduino upload failure

I found installing a 1 uF capacitor between GND and RST helps a lot. See the link for more discussion.

http://community.m5stack.com/topic/55/simple-fix-when-upload-fails

Battery Power On Failure

When running on battery, the M5Stack does not turn on when the USB host module is installed. The M5Stack works fine running on battery but once it is turned off, it can only be turned on by plugging in power via the USB jack.

The M5Stack power on works correctly when the USB host module is removed.