Lithiumate Lite BMS Raspberry Pi Interface Designlithiumate.elithion.com/pdf/AccessLithiumateLiteBMSdataOnHandheldWiFiDevice-r0.1a.pdfLithiumate Lite BMS Raspberry Pi Interface 3/15

Author:

Peter Chave

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Lithiumate Lite BMS Raspberry Pi Interface

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D:\Chi Projects\DugBus\Battery Management\Access Lithiumate Lite BMS data on handheld WiFi device-r0.3.docx

Lithiumate Lite BMS Raspberry Pi Interface Design Aim: To monitor/query BMS stats from a handheld WiFi device such as an iPhone or a video head unit.

Peter Chave ([email protected]), Revision 0.3 – 2/10/2013

EV project: www.stealthbus.net

Revision History Revision 0.1 – Initial beta, using php script to directly exec serial reader.

Revision 0.2 – Re-written using background process to poll BMS and render html.

Revision 0.3 – Cleaned up error reporting, added head unit output.

Contents

1 Access Lithiumate Lite BMS data on handheld WiFi device. .................................................. 2 1.1 System description .................................................................................................................................. 2 1.2 On-line simulation .................................................................................................................................... 2 1.3 Hardware overview .................................................................................................................................. 2 1.4 Software structure ................................................................................................................................... 3 1.5 Web page structure: ................................................................................................................................ 3

2 User interface .............................................................................................................................. 4 2.1 Description .............................................................................................................................................. 4 2.2 Common elements .................................................................................................................................. 4 2.3 Main summary screen ............................................................................................................................. 5 2.4 Navigation to sub pages .......................................................................................................................... 5 2.5 Charging information page ...................................................................................................................... 6 2.6 Voltage history ......................................................................................................................................... 6 2.7 Amp history ............................................................................................................................................. 7 2.8 Per cell voltage graph page .................................................................................................................... 7 2.9 Per cell temperature graph page ............................................................................................................. 8 2.10 Troubleshooting ....................................................................................................................................... 9

3 How to build it ........................................................................................................................... 10 3.1 Hardware required: ................................................................................................................................ 10 3.2 Easy configuration ................................................................................................................................. 10 3.3 Manual configuration steps ................................................................................................................... 10

4 Modifying install ....................................................................................................................... 13

5 Head unit display ...................................................................................................................... 14

6 Future improvements ............................................................................................................... 14

Author:

Peter Chave


Printed: 6/17/2013 4:17:00 PM Title:


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1 Access Lithiumate Lite BMS data on handheld WiFi device.

1.1 System description

A Raspberry Pi (ARM based credit card size computer) is connected to the USB port of the Lithiumate Lite BMS.

The Raspberry Pi (RPi) using a WiFi adapter acts as a hotspot with simple web server. The handheld WiFi device

via its web browser connects to the hotspot accesses a simple HTML/Javascript page. The main page in turn

retrieves a data page which is being generated by a background helper program on the RPi. The helper

program queries the BMS and generates javascript data which then polled by the client and processed by the

browser to render the BMS status information to the user.

Example screen shot:

1.2 On-line simulation

A simulation of the interface look and feel can be viewed on any browser including iPhone.

http://www.stealthbus.net/bmssim/bms.html

1.3 Hardware overview

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Lithiumate BMS is connected via a standard USB cable to USB port on the Raspberry Pi.

A USB WiFi adapter is connected to the second USB port on the RPi.

A WiFi connection is established to the handheld device.

1.4 Software structure

Raspberry Pi running Wheezy (standard distro).

Software installed: apache2 + hostapd + udhcpd + helper program (written in C)

1.5 Web page structure:

Main page is “index.html”, containing basic page layout and javascript rendering routines. On the main page

there is a hidden embedded ‘iframe’, this is used to poll for new values without requiring a full page reload.

The iframe source is a page called bmsdata.html

The background program (bmsd) sends an “x”, “v” and “t” on the serial port for device (default: /dev/ttyUSB0).

The hex string returned from the BMS is parsed into the javascript variables written to the file called

bmsdata.html. At the end of the page returned is call to main page to invoke rendering of the data.

In my system a second iframe is used to query in the background the status of the auxiliary battery and

optionally other analog measurements, if this module is not present, the entry is simply left blank in the

rendered GUI. In a future version I would like to integrate this directly on the RPi (and avoid the 2nd device.)

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Peter Chave


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2 User interface

2.1 Description

The UI is accessed by connecting to the RPi hotspot, and opening a browser to IP address of the RPi.

The page is designed for iPhone usage as mobile application, the first time you access it from safari, if you

select “link to home screen”. A link is placed on the home screen, so the page can be launched just like a native

app. This is nice as it clears the screen of the browser controls.

2.2 Common elements

Tally toggles on and off every 5s. Overall status: NORMAL, WARNING, FAULT or CONNECT ISSUE

Detailed status: Contains description of fault or warning message from BMS

The banners are colored green for OK, yellow for WARNING and red for FAULT. The text on the top banner

changes accordingly. The lower banner displays the warning/fault message from the BMS.

In case of communication issues with BMS, the banner will be colored blue, with the specific error code

displayed in the detailed status area.

A tally is displayed in the upper bar toggling on and off to show that the background task is running. If this does

not toggle, but the page is refreshing normally then an error condition exists with that task.

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2.3 Main summary screen

State of Charge Pack Voltage (min hold) Pack Amps (peak hold)

Aux Battery* Current Cell Min V (hold min : cell ID) Current Cell Max Temp (hold max : cell ID)

*Note on “Aux Battery” reading, this is read from another device in the car. I have a small IP connected PIC

board with 12 channels of ADC. Via a page query the voltage is returned. In a system without that module, the

entry will appear blank. You can easily edit the page to remove it or replace it with another parameter if you

desire.

2.4 Navigation to sub pages

The page interface is designed for a touchscreen; the following areas launch subpages.

Charging information Pack volts history Pack amps history Returns to main page

Per cell voltage graphs Per cell temperature graphs

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2.5 Charging information page

State of Charge Estimated recharge time (at this rate)

Total power required to recharge Estimated cost Estimated recharge time (at this rate)

2.6 Voltage history

Graph scrolls automatically every 5s, complete window shows approximately last 5 minutes. Range is

controlled from the index.html page.

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2.7 Amp history

Graph scrolls automatically every 5s, complete window shows approximately last 5 minutes. Range is

controlled from the index.html page.

2.8 Per cell voltage graph page

Range of graph and coloring options can be controlled by editing the header of the index.html page.

Tapping the graph toggles between the current values and the lowest recorded per cell view.

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2.9 Per cell temperature graph page

Range of graph and coloring options can be controlled by editing the header of the index.html page.

Tapping the graph toggles between the current values and the highest recorded per cell view:

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2.10 Troubleshooting

Fault Likely cause Remedy

Unable to open web page Not connected to host

spot

Check WiFi settings, hotspot

default name is “RPi-BMS”

IP address not set

(DHCP issue)

Test by manually setting IP to

10.1.1.100 / 255.255.255.0

Web server issue Verify apache2 is running and

pages are present in /var/www

Status = “CONNECT ISSUE”, Detailed =

“Unable to open /dev/ttyUSB0”

BMS is not connected Connect BMS to USB port on RPi.

BMS is assigned to

another serial port

Look in /dev and for ttyUSB

entries. Adjust /etc/init.d/bmsd

to match.

Status = “CONNECT ISSUE”, Detailed =

“timeout (x)”

BMS is not powered Turn on ignition or connect AC.

Tally light does not toggle, and status

is not updating

Background task bmsd

is not running

Check running status by “ps –A |

grep bmsd”. Manually start bmsd

and look for error messages

Author:

Peter Chave


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Lithiumate Lite BMS Raspberry Pi Interface 10/15


3 How to build it

3.1 Hardware required:

Component Cost Example(s)

Raspberry Pi $35 http://www.alliedelec.com/lp/120626raso/ http://www.mcmelectronics.com/product/83-14421&scode=GS401&CAWELAID=1599056700?catargetid=1545764029&cagpspn=pla&gclid=COjs9I_517QCFQeynQodOHoA-g

2G (or bigger) SD Card $5-10 http://www.amazon.com/Transcend-Class-Flash-Memory-TS4GSDHC10E/dp/B003VNKNE6/ref=sr_1_2?ie=UTF8&qid=1357759410&sr=8-2&keywords=4gb+sd+card+class+10

USB WiFi $10 http://www.amazon.com/gp/product/B005CLMJLU/ref=olp_product_details?ie=UTF8&me=&seller=

Enclosure $10-20 http://www.amazon.com/gp/product/B008TCUXLW/ref=oh_details_o00_s00_i00

PSU Car 12v - USB 1A $5-10 http://www.amazon.com/2-Port-Charger-Samsung-Victory-Android/dp/B0062D7SR2/ref=pd_sim_sbs_e_4

Total $65-85

3.2 Easy configuration

1. Download the following image on your PC, this is a pre-configured image. It contains the 2012-12-16-

wheezy-raspbian image with apache2, php, hostapd, udhcpd and the custom web pages all ready to go.

http://www.stealthbus.net/src/RPi-image-r0.2.zip

a. Out of the box this image assumes you are using the Edimax USB WiFi, if you used another, you

will need to tweak the driver in the /etc/hostapd/hostapd.conf file.

2. Follow the standard image transfer procedure here, using the prepackaged image you downloaded:

http://www.raspberrypi.org/downloads

3. Insert the SD card into the RPi, connect WiFi USB, the USB cable to BMS and power cable.

4. On your WiFi device, connect to SSID: RPi-BMS (access code is 87654321)

5. Open a browser and point it at http://10.1.1.1

3.3 Manual configuration steps

1. Install standard Raspbain “wheezy” image using instructions here:

http://www.raspberrypi.org/downloads

2. Connect Raspberry Pi (RPi) to HDMI monitor, USB keyboard, internet connection (using on board LAN

port), and WiFi adapter.

3. Power up and at the initial configuration page preform basic configuration

a. Select “expand_rootfs”, so you have full access to the disk.

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b. Select “boot_behaviour” mode option, select “No” for “Should we boot straight to desktop?”

c. Select “Finish”, and answer “Yes” to “Would you like to reboot now”.

4. Once the Pi reboots, login as “pi”, password is “raspberry”.

Install the following packages:

sudo apt-get install apache2 hostapd udhcpd

5. Configure DHCP, modify the following lines in /etc/udhcpd.conf (comment out all others)

start 10.1.1.2

end 10.1.1.20

interface wlan0

remaining yes

opt subnet 255.255.255.0

opt lease 86400

6. Comment out the following line in /etc/default/udhcpd

#DHCPD_ENABLED="no"

7. Modify/add the following to /etc/network/interfaces

allow-hotplug wlan0

iface wlan0 inet static

address 10.1.1.1

netmask 255.255.255.0

#wpa-roam /etc/wpa_supplicant/wpa_supplicant.conf

If your WiFi adapter is natively supported by hostapd in RPi wheezy distro you go on the next step.

If not, like me and you used the EDIMAX EW-7811Un while being the most compact and requires no

external power on the RPi, you will need to recompile hostapd to support this adapter:

Credit: http://www.raspberrypi.org/phpBB3/viewtopic.php?f=46&t=25921

Note: Do not remove the existing copy of hostapd, just compile the new version and swap the bin file.

This is the updated driver “RTL8192xC_USB_linux_v3.4.4_4749.20121105.zip” which can be

downloaded from here:

http://www.realtek.com.tw/downloads/downloadsView.aspx?Langid=1&PNid=21&PFid=48&Level=5&

Conn=4&DownTypeID=3&GetDown=false&Downloads=true

Copy zip file to RPi.

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Peter Chave


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unzip RTL8192xC_USB_linux_v3.4.4_4749.20121105.zip

cd RTL8192xC_USB_linux_v3.4.4_4749.20121105/wpa_supplicant_hostapd

unzip wpa_supplicant_hostapd-0.8_rtw_20120803.zip

cd wpa_supplicant_hostapd-0.8/hostapd

make

sudo make install

sudo cp /usr/local/bin/hostapd /usr/sbin/hostapd

sudo cp ../../rtl_hostapd_2G.conf /etc/hostapd/hostapd.conf

8. Modify the following entries in /etc/hostapd/hostapd.conf

Note: You can you any SSID name you like here.

ssid=RPi-BMS

9. Modify this line in /etc/default/hostapd

DAEMON_CONF="/etc/hostapd/hostapd.conf"

10. Download web page package and install in files

sudo wget “http://www.stealthbus.net/src/RPi-bmsgui-r0.2.tgz” sudo tar –zxvf RPi-bmsgui-r0.2.tgz

sudo cp bin/bmsd /usr/sbin/bmsd

sudo cp init.d/bmsd /etc/init.d/bmsd

sudo update-rc.d bmsd defaults

sudo cp –r www/* /var/www

11. Enable services to start at boot up

sudo update-rc.d hostapd enable

sudo update-rc.d udhcpd enable

sudo update-rc.d bmsd enable

12. Connect the Lithiumate BMS USB port to the RPi.

13. Reboot RPi

14. Verify install, On your WiFi device, connect to SSID: RPi-BMS (access code is 87654321)

15. Open a browser and point it at http://10.1.1.1

Credits: Hotspot setup adapted from: http://elinux.org/RPI-Wireless-Hotspot

Author:

Peter Chave


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4 Modifying install Edit the following file: /etc/init.d/bmsd

The script takes two parameters, the first is the serial port and second is the number of cells in the battery

pack.

You may want to tweak or add things, like change the graph ranges, warning color limits, etc.

Most GUI modification can be achieved by editing the index.html file located in /var/www

At the top of the file is a control parameter section with the key values, simply edit, save and refresh the

browser on the hand held for the new behavior to take effect.

//*************************************************************************************************************

// Modify this section to change GUI behavior to suit your application

//*************************************************************************************************************

// Limits of voltage graph (Y-axis)

var MAX_GRAPH_V = 4.0

var MIN_GRAPH_V = 2.0

// Color thresholds, beyond MIN/MAX color is red, between MIN-LO or MAX-HI color is yellow, else bar is green.

var MAX_CELL_V = 3.8

var HIGH_CELL_V = 3.6

var LOW_CELL_V = 2.9

var MIN_CELL_V = 2.7

// Limits of temperature graph (Y-axis)

var MAX_GRAPH_T = 60

var MIN_GRAPH_T = 0

// Color thresholds, beyond MIN/MAX color is red, between MIN-LO or MAX-HI color is yellow, else bar is green.

var MAX_CELL_T = 50

var HIGH_CELL_T = 40

var LOW_CELL_T = 5

var MIN_CELL_T = 0

// Cost per charge calculations

var PACK_CAPACITY_KWH = 16

var COST_PER_KWH_CENTS = 8

var CHARGE_RATE_1_TEXT = "120v:12A"

var CHARGE_RATE_1_KW = 1.44

var CHARGE_RATE_2_TEXT = "240v:24A"

var CHARGE_RATE_2_KW = 5.76

//*************************************************************************************************************

If you want other parameters or change the query process the source code for the readbms is included in the

tarball. Simple edit the bms.c (in the ~/src directory) and then recompile using:

gcc –o bms bms.c

service bmsd stop

sudo cp bms /usr/sbin/bmsd

service bmsd start

Author:

Peter Chave


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5 Head unit display If you have a head unit you can configure the RPi to output a video signal, which

Since the head unit will be a uni-directional interface, an optional version of page is created. “headunit.html” in

my version I reduce the horizontal size so it displays nicely.

Make midori open by default when X starts and make the page fullscreen.

/etc/xdg/lxsession/LXDE/autostart

@midori -e Fullscreen -a http://127.0.0.1/headunit.html

Disable screen blanking:

/etc/lightdm/lightdm.conf

[SeatDefaults]

xserver-command=X -s 0 dpms

This was adapted from: http://www.raspberrypi.org/phpBB3/viewtopic.php?f=41&t=924&start=25

6 Future improvements In no specific order, ideas to add or enhance design:

- Integrate aux battery monitoring onto RPi board.

o Using possibly this module: http://www.abelectronics.co.uk/products/3/Raspberry-Pi/17/ADC-

Pi-V2---Raspberry-Pi-Analogue-to-Digital-converter

- Export logging data ( via browser ‘file download’ )

- Make configuration parameters modifiable via the web GUI.

- Add either LCD or LED display to show charging status externally from the car (so at public charging

stations people can see if my car is charged before unplugging).

Thanks for your interest.

Peter Chave ([email protected])

EV Project: www.stealthbus.net

Author:

Peter Chave


Printed: 6/17/2013 4:17:00 PM Title:



Documents

Lithiumate Lite BMS Raspberry Pi Interface Designlithiumate.elithion.com/pdf/AccessLithiumateLiteBMSdataOnHandheldWiFiDevice-r0.1a.pdfLithiumate Lite BMS Raspberry Pi Interface 3/15