$ lpstat -v device for Epson_Stylus_Photo_R2000: lpd://192.168.1.214:515/PASSTHRU $ escputil -P Epson_Stylus_Photo_R2000 -n Escputil version 5.3.3, Copyright (C) 2000-2006 Robert Krawitz Escputil comes with ABSOLUTELY NO WARRANTY; for details type 'escputil -l' This is free software, and you are welcome to redistribute it under certain conditions; type 'escputil -l' for details. Running nozzle check, please ensure paper is in the printer.
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Not everything is ready, there are some broken links etc, but the main part of the blog has been moved.
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OpenCyclingComputer update
OpenCyclingComputer is finally reaching the “road ready” stage:
What works:
- BLE connection with heart rate sensor. Also automatic re-connection and graceful quiet handling of all errors from bluez stack.
- BLE connection with speed and cadence sensor. It’s really wheel revolution and cadence sensor, but given wheel size it works as speed sensor.
- Pressure sensor. Iit will be used as an altimeter in the near future. Coded with Kalman filter
- Temperature sensor
- GPS module – I still need to do some debugging here, but the drivers were tested on raspberry A+ and worked great.
- YAML layouts. It’s very easy to change the default layout – it’s simply a text file + some background images.
- Saving / reading config file. Also YAML, so it’s a human editable.
- “Animated” heart rate and cadence icons showing that the related sensors are “alive” and keep sending notifications.
- All settings can be edited from the OCC screen
Things that need polishing:
- Calculating averages (speed, heart rate, etc)
- Implementing Kalman filters where suitable
- BLE scanning and selecting devices from the OCC screen
- Calculating altitude and all related parameters like slope, pressure at sea level and others
- BLE status icon works, but it doesn’t show exactly what’s happening with the connection
- Implementing Low Battery warning/shut down (hardware is ready)
- Improving ride log. Currently the format of the log is hard coded
Code develpoment:
- defining sensor API for future extensions
- plugging accelerometer into the current system
- implementing inertion+gps navigation with multi input Kalman filter
- code cleaning and refactoring
I used to use pygame, but outdated SDL problems resulting in malfunctioning touchscreen forced me to use a different solution. Touchscreen works with python-evdev and I needed graphics. Cairo is the obvious choice for 2D and after a few days of playing with different solutions I came up with this:
#Very simple way of accessing PiTFT 240x320 display from python with cairo
import mmap
import cairo
# 320 * 240 * 2 bytes per pixel = 153600
PiTFT_mem_size = 153600
# Framebuffer file, might be /dev/fb0
fb_fd = open("/dev/fb1", "r+")
#Map the framebuffer to memory
fb_map = mmap.mmap(fb_fd.fileno(), PiTFT_mem_size)
#Create cairo surface. If you get "Function not implemented" error, you need a newer cairo
surface = cairo.ImageSurface.create_for_data(fb_map, cairo.FORMAT_RGB16_565, 240, 320)
#Create cairo context
cr = cairo.Context(surface)
# Paint the surface black
cr.set_source_rgba (0.0, 0.0, 0.0, 1.);
cr.paint_with_alpha (1.0);
for i in range(0, 10):
c = i / 10.0
cr.set_source_rgb (1.0 - c, 1.0 - c, 1.0)
cr.rectangle(15 * i + 10, 15 * i + 20, 100, 100)
cr.fill ()
#Close the mapped framebuffer
fb_map.close()
That’s how it looks on the piTFT:
Pi Zero W is the new brain of the Open Cycling Computer. PiTFT 2.8″ capacitive dosn’t work out-of-the-box, but required modification are very simple.
Modifications required in /boot/config.txt
1. Uncomment dtparam=spi=on
2. Add dtoverlay=pitft28-capacitive,rotate=90,speed=32000000,fps=20
Modifications required in /boot/cmdline.txt
1. Add after rootwait (the end of line) fbcon=map:10 fbcon=font:VGA8x8 logo.nologo
That’s it! No other modifications are required.
P.S. 31-Mar-2017: Do not install adafruit kernel as it doesn’t support bluetooth/wifi on Pi Zero W yet.
$ ./btle.py fd:df:0e:4e:76:cf random Connecting to: fd:df:0e:4e:76:cf, address type: random Service <uuid=Generic Access handleStart=1 handleEnd=7> : Characteristic <Device Name>, hnd=0x2, supports READ WRITE -> 'Lezyne S&C 249' Characteristic <Appearance>, hnd=0x4, supports READ -> '\x85\x04' Characteristic <Peripheral Preferred Connection Parameters>, hnd=0x6, supports READ -> '\x80\x02H\x03\x00\x00\x90\x01' Service <uuid=Cycling Speed and Cadence handleStart=12 handleEnd=22> : Characteristic <CSC Measurement>, hnd=0xd, supports NOTIFY Characteristic <CSC Feature>, hnd=0x10, supports READ -> '\x07\x00' Characteristic <Sensor Location>, hnd=0x12, supports READ -> '\x04' Characteristic <SC Control Point>, hnd=0x14, supports INDICATE WRITE Service <uuid=Generic Attribute handleStart=8 handleEnd=11> : Characteristic <Service Changed>, hnd=0x9, supports INDICATE Service <uuid=00001530-1212-efde-1523-785feabcd123 handleStart=30 handleEnd=65535> : Characteristic <00001532-1212-efde-1523-785feabcd123>, hnd=0x1f, supports WRITE NO RESPONSE Characteristic <00001531-1212-efde-1523-785feabcd123>, hnd=0x21, supports NOTIFY WRITE Characteristic <00001534-1212-efde-1523-785feabcd123>, hnd=0x24, supports READ -> '\x01\x00' Service <uuid=Battery Service handleStart=23 handleEnd=26> : Characteristic <Battery Level>, hnd=0x18, supports NOTIFY READ -> 'd' Service <uuid=Device Information handleStart=27 handleEnd=29> : Characteristic <Manufacturer Name String>, hnd=0x1c, supports READ -> 'Lezyne'
I have a fairly large photo collection on a raspberry pi based NAS. Unfortunately RPI ethernet port is not fast enough (100MB/s) for comfortable remote operation, so to be able to use that collection I have to keep local thumbnail directory on my linux box. Gnome nautilus is my tool of choice, but nautilus generates thumbnails only after entering a directory. To make that setup workable I had to:
1. Make sure gnome allows big thumbnails and doesn’t expire them: dconf-editor, go to org->gnome->desktop->thumbnail-cache and set maximum-age and maximum-size to -1
2. Generate the thumbnails
Nautilus thumbnails are saved in png files with name like this: 00067ecff5de0e48602327bc987f6d9a.png. The name is md5sum of image path with spaces replaced by %20. The path is not an absolute path in the system! So for example I have a photo at /run/user/1000/gvfs/sftp:host=192.168.1.231,user=pi/mnt/PhotoArchive/Dump/a_photo.jpg, but the path nautilus uses to generate thumbnail name is sftp://pi@192.168.1.231/mnt/PhotoArchive/Dump/a_photo.jpg (it can be checked in nautilus – just right click on an image and check location). Local files have prefix file://
I had some problems with getting reliable results for a find command run on a remote system, so I decided to create 2 scripts to generate the thumbnails. The first script scans (scan.sh – BROKEN LINK) remote location for images, generates md5sum for the image path and, if there is no thumbnail stored locally, writes the file path to a pipe. Another script (thumbnail.sh –BROKEN LINK) waits for whatever shows up in the pipe and generates the thumbnail. An example usage:
./scan.sh /run/user/1000/gvfs/sftp:host=192.168.1.231,user=pi mnt/ sftp://pi@192.168.1.231
and in a separate terminal:
./thumbnail.sh /run/user/1000/gvfs/sftp\:host\=192.168.1.231\,user\=pi/ sftp://pi@192.168.1.231
Legend:
/run/user/1000/gvfs/sftp\:host\=192.168.1.231\,user\=pi/ <– I have my NAS mounted at that point ($ROOT_DIRECTORY)
mnt/ <–the scripts scan should scan that directory and all subdirectories ($IMAGE_DIRECTORY)
sftp://pi@192.168.1.231 <– path prefix used by nautilius for that location to generate md5sum ($PREFIX)
I used those 2 script to generate over 65.000 (6 GB) of thumbnails. The directory where thumbnails are saved is hardcoded in thumbnail.sh (THUMBNAIL_DIR=/home/przemo/.cache/thumbnails/large/) – please update before using the script!
It’s a short guide to practical side of bluetooth LE using gatttool. How to read characteristics, turn on notifications and where to find more info about all those BLE numbers.
I was struggling for a while to read data from a BLE heart rate strap. It was working flawlessly with android apps, but I needed it to use it with raspberry pi and python. So, I had to dig a bit deeper under the surface of BLE. The results are below.
Prerequisites:
1. A computer with bluetooth v4.0 card or dongle
2. gatttool (part of bluez). Fedora users might have to compile bluez as there is no gatttool in bluez-5.23-1.fc21 bugreport: [1].
3. A BLE (bluetooth Low Energy, Bluetooth Smart) device – I use a Tacx heart rate belt [2]
An example command line session (red – important or info for later use, blue – value from previous steps, green – comment):
$ hciconfig hci0: Type: BR/EDR Bus: USB ^^ hci0: that's our hci device BD Address: C4:85:08:06:9F:C7 ACL MTU: 310:10 SCO MTU: 64:8 UP RUNNING PSCAN RX bytes:10243057 acl:34567 sco:0 events:5307 errors:0 TX bytes:46612 acl:737 sco:0 commands:2685 errors:0 fedora-lan:/home/przemo $ sudo hciconfig hci0 up fedora-lan:/home/przemo $ sudo hcitool -i hci0 lescan LE Scan ... <-- LE Scan was not showing anything, so Ctrl-C and hci0 reset ^Cfedora-lan:/home/przemo $ sudo hciconfig hci0 reset fedora-lan:/home/przemo $ sudo hcitool -i hci0 lescan LE Scan ... D6:90:A8:08:F0:E4 Tacx HRB 04741 ^^ D6:90:A8:08:F0:E4 that's BLE device address D6:90:A8:08:F0:E4 (unknown) D6:90:A8:08:F0:E4 Tacx HRB 04741 D6:90:A8:08:F0:E4 (unknown) ^Cfedora-lan:/home/przemo $ sudo gatttool -i hci0 -b D6:90:A8:08:F0:E4 -t random -I ^^ if you can't connect try to use "-t random" [D6:90:A8:08:F0:E4][LE]> connect Attempting to connect to D6:90:A8:08:F0:E4 Connection successful Reading value of battery level characteristic [D6:90:A8:08:F0:E4][LE]> primary attr handle: 0x0001, end grp handle: 0x0007 uuid: 00001800-0000-1000-8000-00805f9b34fb attr handle: 0x0008, end grp handle: 0x000b uuid: 00001801-0000-1000-8000-00805f9b34fb attr handle: 0x000c, end grp handle: 0x0011 uuid: 0000180d-0000-1000-8000-00805f9b34fb attr handle: 0x0012, end grp handle: 0x0015 uuid: 0000180f-0000-1000-8000-00805f9b34fb ^^^ 180f is "Battery Service", see link [3] attr handle: 0x0016, end grp handle: 0xffff uuid: 0000180a-0000-1000-8000-00805f9b34fb [D6:90:A8:08:F0:E4][LE]> characteristics 0x0012 0x0015 handle: 0x0013, char properties: 0x12, char value handle: 0x0014, uuid: 00002a19-0000-1000-8000-00805f9b34fb ^^ 2a19 is Battery Level, links [4] and [5] char properties 0x12: supports NOTIFICATION 0x10 and READ 0x02 (0x10 | 0x02 = 0x12) [D6:90:A8:08:F0:E4][LE]> char-read-hnd 0x0014 ^^ Reading handle value Characteristic value/descriptor: 64 ^^ value of battery level is 64, but it's hex, so 0x64 = 100. It's in %, link [4]
Reading heart rate [D6:90:A8:08:F0:E4][LE]> primary attr handle: 0x0001, end grp handle: 0x0007 uuid: 00001800-0000-1000-8000-00805f9b34fb attr handle: 0x0008, end grp handle: 0x000b uuid: 00001801-0000-1000-8000-00805f9b34fb attr handle: 0x000c, end grp handle: 0x0011 uuid: 0000180d-0000-1000-8000-00805f9b34fb ^^ 180d is "Heart Rate" service, link [3] attr handle: 0x0012, end grp handle: 0x0015 uuid: 0000180f-0000-1000-8000-00805f9b34fb attr handle: 0x0016, end grp handle: 0xffff uuid: 0000180a-0000-1000-8000-00805f9b34fb [D6:90:A8:08:F0:E4][LE]> characteristics 0x000c 0x0011 handle: 0x000d, char properties: 0x10, char value handle: 0x000e, uuid: 00002a37-0000-1000-8000-00805f9b34fb ^^ 2a37 is Heart Rate characteristic, links [5] and [6] char properties: 0x10: supports NOTIFICATION handle: 0x0010, char properties: 0x02, char value handle: 0x0011, uuid: 00002a38-0000-1000-8000-00805f9b34fb ^^ 2a38 is Body Sensor Location, links [6] and [7] char properties: 0x02: supports READ [D6:90:A8:08:F0:E4][LE]> char-read-hnd 0x0011 ^^ Reading Body Sensor Location Characteristic value/descriptor: 01 ^^ 0x01 it's "Chest", see link [7] for more options We need more info to switch on NOTIFICATION of heart rate [D6:90:A8:08:F0:E4][LE]> char-desc 0x000d 0x000f ^^ range of handles for heart rate: 0x000d is start of the range obtained with 'characteristics 0x000c 0x0011' 0x0010 is start of next characteristic minus 1: 0x0010 - 0x1 = 0x000f handle: 0x000d, uuid: 00002803-0000-1000-8000-00805f9b34fb handle: 0x000e, uuid: 00002a37-0000-1000-8000-00805f9b34fb handle: 0x000f, uuid: 00002902-0000-1000-8000-00805f9b34fb ^^ 2902 it is Client Characteristic Configuration, link [8] [D6:90:A8:08:F0:E4][LE]> char-write-cmd 0x000f 01 ^^ 01 comes from link [8], NOTIFICATIONS enabled Notification handle = 0x000e value: 00 3e <-- heart rate, 0x003e is 63 BPM Notification handle = 0x000e value: 00 3d <-- heart rate, 0x003d is 62 BPM Notification handle = 0x000e value: 00 3d <-- heart rate, 0x003d is 62 BPM Notification handle = 0x000e value: 00 3c <-- heart rate, 0x003c is 61 BPM [D6:90:A8:08:F0:E4][LE]> char-write-cmd 0x000f 00 ^^ 00 comes from link [8], NOTIFICATIONS disabled [D6:90:A8:08:F0:E4][LE]> disconnect <-- end of connection [D6:90:A8:08:F0:E4][LE]> fedora-lan:/home/przemo/android
[1] https://bugzilla.redhat.com/show_bug.cgi?id=1141909
[2] http://www.tacx.com/en/products/sensors/heart-rate-belt
[3] https://developer.bluetooth.org/gatt/services/Pages/ServicesHome.aspx
[5] https://developer.bluetooth.org/gatt/characteristics/Pages/CharacteristicsHome.aspx
MMA88451 doesn’t work with raspbterry pi out of the box. It needs I2C with repeated start. Test program in python:
import smbus
DEVICE_ADDRESS = 0x1d
MMA8451_REG_WHOAMI = 0x0D
bus = smbus.SMBus(1)
ret = bus.read_byte_data(DEVICE_ADDRESS, MMA8451_REG_WHOAMI)
print retShows zero instead of expected 26 (0x1A in hex)
pi@occberry ~/OpenCyclingComputer $ sudo python src/mma8451.py
0Solution that I found here solves the problem:
sudo chmod 666 /sys/module/i2c_bcm2708/parameters/combined
sudo echo -n 1 > /sys/module/i2c_bcm2708/parameters/combined
and now the python test code shows, as expected:pi@occberry ~/OpenCyclingComputer $ sudo python src/mma8451.py
26[1] www.adafruit.com/products/2019
[2] www.raspberrypi.org/forums/viewtopic.php?f=44&t=15840&start=25