SingletonMillerWiki - User contributions [en]

Talk:Tty setup

2012-10-15T15:20:08Z

BillyBag2: Created page with "(BillyBag2) Should add some pictures to this page. Also add more about stty command. Also is tty0 the built in UART going to the GPIO port?"

(BillyBag2) Should add some pictures to this page. Also add more about stty command. Also is tty0 the built in UART going to the GPIO port?

Tty setup

2012-10-15T15:18:22Z

BillyBag2: /* Built in UART */ Added more information.

= Configuring a TTY serial port=
tty devices are found in the /dev directory. If you use a USB adapter it will appear as /dev/ttyusb0.

Use the ''stty'' command to configure tty devices.
= Hardware =
== Built in UART ==
The built in UART is connected to the GPIO connector P1. NOTE: These signals are unbuffered 3.3v logic and NOT RS232 OR 5v TTL compatible. To use the built in UART to a standard RS232 device a MAX RS232 chip is required. The MAX3232 is a commonly used chip. The chip itself can run at 3.3 and 5v. You MUST run it off the 3.3v supply if it is connected to the RPi. A MAX3232 can be purchased already mounted with the external components. This is simpler and possibly cheaper than mounting the chip yourself.

Modules, such as [[GPS]], often use standard digital signals rather than RS232 voltages. Check their specs carefully. Some are 3.3v based. Others are 5V but you may find the output is 3.3v "compatible". If it is 5v and does not mention 3.3v compatibility, do not connect it directly to the Pi. It is always wise to add some buffering to the Pi's IO as it is unprotected. See the buffer board as an example.

== USB to RS232 ==
=== Successful ===
A PL-2303 based USB to RS2323 adapter work on my Raspbian based Pi without installing additional drivers, although it was not a fully clean install.
=== Recommended ===
I have used FTDI devices with other projects, these are also discussed in many Pi forums. I (BillyBag2) have not used these on a Pi myself. These tend to be more expensive.
=== Not successful ===
The cheapest adapters are "340" based. HOWEVER I (BillyBag2) was unable to get these to work fully.

Tty setup

2012-10-15T15:10:39Z

BillyBag2: Added some info about TTY, serial and RS232.

User:BillyBag2

2012-10-15T14:40:43Z

BillyBag2: Created page with "= Software Engineer = I'm an embedded C software engineer. = Raspberry Pi Hobbyist = I have three Pis and many little projects on the go. (none are finished) = Blogger = Some Ras..."

= Software Engineer =
I'm an embedded C software engineer.
= Raspberry Pi Hobbyist =
I have three Pis and many little projects on the go. (none are finished)
= Blogger =
Some Raspberry Pi blogs at http://pinchips.blogspot.co.uk.

GPS

2012-10-13T01:21:50Z

BillyBag2: Added categories

[[Category:RaspberryTortoise]] [[Category:RaspberryPi]]
== Candidates ==
=== Garmin Geko 301 ===
The [https://buy.garmin.com/shop/shop.do?pID=221 Garmin Geko 301] is a candidate GPS for use with the Raspberry Pi on projects such as RaspberryTortoise. It is an obsolete hand held GPS system designed for Hiking and GPS games.

==== Advantages ====
#Small and low power for a hand held GPS.
#Differential GPS that gives added accuracy, this works in the UK using free european satellites designed to provide this additional differential GPS service.
#Electronic compass to provide orientation.
#Supports standard NMEA messages
#RS232 serial is simple to use
#Barometer for altitude. (For when RaspberryTortoise gets its rocket pack)
#Acts as a GPS data logger
#Has potential to contain preloaded tracks or waypoints for navigation.
#Will potentially calculate additional information such as speed or distance away from a route.
#Software available to manage data on GPS.
#Obsolete and can be found for sale second hand. (not colour or USB so considered outdated)

==== Disadvantages ====
#Bigger than a GPS module
#Requires two AAA batteries or a 3.0v supply. (3.3v is NOT close enough)
#Connector is not standard.
#RS232 level outputs require level shifter for Raspberry Pi input.
#Discontinued.
#Only 1Hz sample rate. Some GPS modules are 10Hz
#Relatively difficult to mount, while sill in case and when removed from case.

GPS

2012-10-13T01:18:11Z

BillyBag2: /* Disadvantages */ Added sample rate a mounting issues.

== Candidates ==
=== Garmin Geko 301 ===
The [https://buy.garmin.com/shop/shop.do?pID=221 Garmin Geko 301] is a candidate GPS for use with the Raspberry Pi on projects such as RaspberryTortoise. It is an obsolete hand held GPS system designed for Hiking and GPS games.

==== Advantages ====
#Small and low power for a hand held GPS.
#Differential GPS that gives added accuracy, this works in the UK using free european satellites designed to provide this additional differential GPS service.
#Electronic compass to provide orientation.
#Supports standard NMEA messages
#RS232 serial is simple to use
#Barometer for altitude. (For when RaspberryTortoise gets its rocket pack)
#Acts as a GPS data logger
#Has potential to contain preloaded tracks or waypoints for navigation.
#Will potentially calculate additional information such as speed or distance away from a route.
#Software available to manage data on GPS.
#Obsolete and can be found for sale second hand. (not colour or USB so considered outdated)

==== Disadvantages ====
#Bigger than a GPS module
#Requires two AAA batteries or a 3.0v supply. (3.3v is NOT close enough)
#Connector is not standard.
#RS232 level outputs require level shifter for Raspberry Pi input.
#Discontinued.
#Only 1Hz sample rate. Some GPS modules are 10Hz
#Relatively difficult to mount, while sill in case and when removed from case.

GPS

2012-10-13T01:15:03Z

BillyBag2: /* Advantages */ Minor tweak

GPS

2012-10-13T01:12:56Z

BillyBag2: Added a suggestion that a Garmin Geko 301 could be used with the raspberry pi.

== Candidates ==
=== Garmin Geko 301 ===
The [https://buy.garmin.com/shop/shop.do?pID=221 Garmin Geko 301] is a candidate GPS for use with the Raspberry Pi on projects such as RaspberryTortoise. It is an obsolete hand held GPS system designed for Hiking and GPS games.

==== Advantages ====
#Small and low power for a hand held GPS.
#Differential GPS that gives added accuracy, this works in the UK using free european satellites designed to provide this additional differential GPS service.
#Electronic compass to provide orientation.
#Supports standard NMEA messages
#RS232 serial is simple to use
#Barometer for altitude. (For when RaspberryTortoise gets its rocket pack)
#Acts as a GPS data logger
#Has potential to contain preloaded tracks or waypoints for navigation.
#Will potentially calculate additional information such as speed or distance away from a route.
#Software available to manage data on GPS.

==== Disadvantages ====
#Bigger than a GPS module
#Requires two AAA batteries or a 3.0v supply. (3.3v is NOT close enough)
#Connector is not standard.
#RS232 level outputs require level shifter for Raspberry Pi input.
#Discontinued.

RaspberryTortoise

2012-10-13T00:49:51Z

BillyBag2: /* Added a link to a GPS page */

[[Category:RaspberryPi]]
[[Category:Projects]]
[[Category:RaspberryTortoise]]

The [[RaspberryTortoise]] is a project aiming to develop a motorised roving vehicle from readily available components and a Raspberry Pi single board computer(soon to be readily available).

=== Status ===
This project has reached the deploy and test stage. If you'd like to get involved contact us.
To see the Tortoise head over to the [http://www.youtube.com/channel/UCiRSha1Vqncz_YmlbY03JnA?feature=watch| YouTube Channel]

== Current Objective ==

Integrate the Encoders into the control loop.

== Ambitions ==
This is a list of the things we hope to achieve with the Tortiose.
#Network enabled communications (wifi & SSH) '''--complete'''
#Web enabled controls '''--complete'''
#Visual Feedback (camera) '''--complete'''
#Semi-Autonomous operations
##Object Detection & Avoidance
##Object Tracking / Chase
##Environment Exporation and mapping ([[GPS]]?)
##Area Patrol
#Control via Playstation controller?

== Components ==

The current design incorporates the following components.

#System Controller: RaspberryPi + [[RaspberryPi_Buffer_Board]]
#Operating System: Raspian [[Setup:RPI Raspian]]
#Platform: Modified BigTrak [[Big Trak Autopsy]]
#Sensors: Webcam
#Interfaces: [[Installing EW-7811Un WifiDongle]]
#Software: [[Tortoise GitHub]]
#Power: Battery and Voltage regulation

=== Buffer Board ===
[[RaspberryPi_Buffer_Board]] is used to protect the control interfaces from the RPi.

=== Operating System ===
Raspian has been selected for is hard floating point support which 'should' provide a performance improvement.

=== Platform ===
[[File:800px-Big_trak_white_background.jpg|200px|thumb|right|800px-Big_trak_white_background.jpg]]
The chosen platform for the RaspberryTortoise is a BigTrak [http://en.wikipedia.org/wiki/Big_Trak].

BigTraks were a popular motion-programmable 'robot' vehicle originally released in the late 1970s through to the 1980's.

These vehicles have been making a come-back as a 'nostalgia' toy. The are relatively cheap and contain all the key components needed to make a working robot.

Prior work has identified the major components of the original BigTrak were simple[http://www.robotroom.com/BigTrak.html].
The 2010 variant of the Big Trak is superficially the same, however the control systems and power have been updated. [[Big Trak Autopsy]].

The modern BigTrak circuits has been partially reverse engineered [[Big Trak Circuits]]. From which we've identified the primary motor drives and encoder connections.

=== Sensors ===
==== WebCam ====
Ideally this should be the [http://www.raspberrypi.org/archives/1254 Raspberry Pi Camera Module], however this is still under development and not available.

As an alternative, just about any Linux support webcam will do but the [http://www.microsoft.com/hardware/en-us/p/lifecam-cinema/H5D-00001 Microsoft Corp. LifeCam Cinema] is the recommended camera.

Imagery is streamed to the User using Motion and a Webpage.

=== Interfaces ===
A wifi dongle is fitted to one of the RPi USB ports to provide network connectivity and remote access.

=== Software ===

The Tortoise runs on a Raspian installation base.

Github is used to store all the bespoke software needed for the project here: [[Tortoise GitHub]]

==== Installation Instructions ====
In general the best instructions are provided in the GIt readme file.

The process is
# Create a vanilla Raspian image [[Setup:RPI Raspian]]
# Install the Wifi Dongle and Update [[Installing_EW-7811Un_WifiDongle]]
# Install motion, nodejs and git
# Download the Tortoise git repository
# Follow Git readme for configuration of motion and nodejs.

* [[RaspberryTortoise Web Server]]

=== Power ===
The current design uses a 6V(4500mAH) NiMH battery which can supply 1A. This is directly connected to the RPi which in turn supplies the USB ports with the powered needed to run the Wifi Dongle and the Camera.

The Battery is also wired directly to the BT main board to provide the power to the motors.

==== Power Budget ====
{| class="wikitable" style="text-align: center; width: 200px; height: 200px;"
|+ Estimated Power Consumption
|-
! scope="col" | device
! scope="col" | Voltage (V)
! scope="col" | Current (mA)
! scope="col" | Peak Current (mA)
|-
| RPi
| 5.0 || 200-300 || 300
|-
| Main Board
| 3.3 || 100 || 100
|-
| BT Motors
| 4.5 || 50 || 150
|-
| USB Wifi
| 5.0 || 100 || ?
|-
| USB Camera
| 5.0 || 100 || ?
|-
|}

Tests are required to confirm these values.
It has been shown that the power consumption of an RPi can be reduced by replacing the linear regulator of the RPi[http://www.bitwizard.nl/wiki/index.php?title=Reducing_power_consumption_of_a_raspberry_Pi].

==== Power Regulation ====
The RPi requires 5V and generates its own 3.3V. The motor drive requires 4.5V and the main board 3.3V.
The expectation is that the motors will not be adversely affected by running from 5V and that we can use the RPi 3.3v to run the main servo board assuming the current consumption isn't too high.

The plan is to use batteries with a power regulator to generate the 5V.
[[File:LM2596 DC-DC Step Down CC-CV Adjustable Power Supply Module Output DC 1.5V-35V.png|200px|thumb|right|LM2596 DC-DC Step Down]]

==== Batteries ====
Adding an RPi and associated peripherals is expected in increase the load such that more battery capacity is required to achieve 'reasonable' run-time.

Any reasonable capacity battery should do if it provides enough head room to run the power regulation module.

[http://www.pilot-batteries.url.tw/pdf/6v1/PL4-6_AGM_.pdf|Pilot PL4-6 6V 4.5AH Lead Acid battery] runs the Pi and the BigTrak without any regulation although the pi on board regulator does have to dissapate a little heat.

Alternatives include: (some may require regulation).
* Buy a cheap cordless drill and hack it to get the battery, bonus it comes with a charger too!
* Possible rechargable batteries [http://quadcopters.co.uk/lipo-batterys-61-c.asp][http://www.overlander.co.uk/batteries-chargers/lipo-batteries.html]
* Solar Cell for daylight operation or to recharge / top-up battery [http://www.robotroom.com/Solar-Recharging.html]
* 5V 11000mAH battery used in other RPi projects [http://www.amazon.co.uk/gp/product/B004CHMP50/ref=as_li_tf_tl?ie=UTF8&tag=jersblo00-21&linkCode=as2&camp=1634&creative=6738&creativeASIN=B004CHMP50][http://www.newtrent.com/store/iphone-external-battery/icruiser.html]
* DC-DC Step Down Ajustable PSU Module LM2796 Switch Regulator 4.5-35V to 1.25-26V [http://www.ebay.co.uk/itm/DC-DC-Step-Down-Ajustable-PSU-Module-LM2796-Switch-Regulator-4-5-35V-to-1-25-26V-/290637909304?pt=UK_BOI_Electrical_Test_Measurement_Equipment_ET&hash=item43ab5e8d38]

== Vehicle Interface ==
The BT main board has 4 PWM inputs to drive the Left and Right motors forwards and backwards.

To control this from the RPi which only has one PWN output a small series of enables is used. [[link needed]]

These enables are attached to RPi GPIO and controlled via the motor drive software.

Basic functionality for Forward, Backward, Left and Right has been implemented.

Development of an improved Interface planned which should provide capability for more sofisticated motion control.

== Key Pad ==
We don't currently expect to use the key pad but it might be useful at some point.

There are 10 connections on the main board which somehow map to the rows and columns of the key pad via the main IC.

The keypad appears to be the same layout as the original BigTrak, its assumed to be some kind of mebrane key pad[http://en.wikipedia.org/wiki/Membrane_keyboard].

The keypad on the BTJunior has been investigated[http://www.nathandumont.com/node/248] and reported to be very difficult to understand and emulate.
It seems plausible the bigger variant will be similarly complex.

== References ==
#[http://en.wikipedia.org/wiki/Big_Trak http://en.wikipedia.org/wiki/Big_Trak]
#[http://www.robotroom.com/BigTrak.html Big Trak Reverse Engineered by Robot Room]
#[http://www.raspberrypi.org/archives/260 http://www.raspberrypi.org/archives/260]
#[http://www.robotroom.com/Big-Trak-3.html Robot Room Big Trak Motor Drivers]
#[http://www.bitwizard.nl/wiki/index.php?title=Reducing_power_consumption_of_a_raspberry_Pi RPi power reduction]
#[http://quadcopters.co.uk/lipo-batterys-61-c.asp Possible Rechargable Batteries]
#[http://www.overlander.co.uk/batteries-chargers/lipo-batteries.html More high capacity but expensive batteries]
#[http://www.robotroom.com/Solar-Recharging.html Solar Recharging]
#[http://www.newtrent.com/store/iphone-external-battery/icruiser.html http://www.newtrent.com/store/iphone-external-battery/icruiser.html]
#[http://www.ebay.co.uk/itm/DC-DC-Step-Down-Ajustable-PSU-Module-LM2796-Switch-Regulator-4-5-35V-to-1-25-26V-/290637909304?pt=UK_BOI_Electrical_Test_Measurement_Equipment_ET&hash=item43ab5e8d38 DC-DC Step Down Ajustable PSU Module LM2796 Switch Regulator 4.5-35V to 1.25-26V]
#[http://www.nathandumont.com/node/248 http://www.nathandumont.com/node/248 BT Junior Hacked]
#[http://www.raspberrypi.org/archives/1254 RPi Camera module]

== Resources / Research ==
#[http://www.expresspcb.com/ PCB manufacture]
#[http://www.giantshark.co.uk/chargers-c-27.html Battery Chargers]
#[http://www.autoexpress.co.uk/products/products/278470/bigtrak_xtr_review.html BigTrak updated for 2012?]
#[http://www.bigtrakisback.com/xtr-coming-soon/ bigtrakisback.com]
#[http://blog.ianrenton.com/tag/raspberry-tank-build-diary/?order=asc Raspberry Pi tank]
#[http://www.ebay.co.uk/itm/12V-Rechargeable-Li-po-Battery-for-CCTV-Cam-6800mAh-2-/290656714473?pt=UK_ConsumerElectronics_Batteries_SM&hash=item43ac7d7ee9 12V battery kit Ebay]

Big Trak Circuits

2012-10-13T00:26:40Z

BillyBag2: /* Suggested reuse of cable restraint */

[[Category:RaspberryTortoise]]

This page documents the circuit inside the new Big Trak.

== General Information ==
There are two know revisions of Big Traks. The main features of both designs remain the same but Rev 2.0 has a different circuit card assembly and a 3 pole not 2 pole switch.

Both Big Trak circuits are powered by 3 x 1.5v batteries. This is regulated to 3.3v by IC1 on the circuit board with all the board running off this 3.3v supply. The only exception are the motors which are powered by the un-regulated 4.5volts.

=== Rev 1.0 IC Pinouts ===
[[File:IC2.jpg|200px|IC2 Pinouts]]
{| class="wikitable" style="text-align: center; width: 300px; height: 200px;"
|+ IC2 Pinouts
|-
! scope="col" | Pin Number
! scope="col" | Input / Output
! scope="col" | Description
|-
! scope="row" | 1
| ? || ?
|-
! scope="row" | 2
| Output || ML- CTRL
|-
! scope="row" | 3
| Output || ML+ CTRL
|-
! scope="row" | 4
| Output || MR- CTRL
|-
! scope="row" | 5
| Output || MR+ CTRL
|-
! scope="row" | 6
| ? || ?
|-
! scope="row" | 7
| INPUT || CTRL (from IC3)
|-
! scope="row" | 8
| INPUT || CTRL (from IC3)
|-
! scope="row" | 9
| INPUT || CTRL (from IC3)
|-
! scope="row" | 10
| INPUT || CTRL (from IC3)
|-
! scope="row" | 11
| ? || ?
|-
! scope="row" | 12
| INPUT || 3v3
|-
|}

=== Rev 2.0 IC Pinouts ===
If you can safely remove the main IC, then then the pads remaining are a good point to jack in your RPi control lines.

{| class="wikitable" style="text-align: center; width: 400px; height: 200px;"
|+ Main IC Pinouts
|-
! scope="col" | Pin Number
! scope="col" | Input / Output
! scope="col" | Description
|-
| 1 || Input || Motor Left -ve PWM
|-
| 6 || Input || Encoder Enable
|-
| 17 || Output || Left Encoder Feedback
|-
| 18 || Output || Right Encoder Feedback
|-
| 28 || Input || Motor Right +ve PWM
|-
| 29 || Input || Motor Right -ve PWM
|-
| 30 || Input || Motor Left +ve PWM
|}

== Motor Control ==
Big Trak contains a H-bridge Motor Control circuit that makes it possible to rotate the motor in both direction from a single power source. In this case it is 4.5volts. The circuit diagram below shows the left hand side motor control circuit. The circuit is the same for the right hand side.

[[File:mototcontrol.jpg|800px|Big Trak Motor Control Circuit]]

To make the motor rotate in a forward direction a positive voltage is applied to the forward input whilst the reverse input is pulled low. With these inputs transistors Q5 and Q13 will conduct allowing current to flow through the motor. To reverse the motor direction a positive voltage is applied to the reverse input while pulling the forward input low. This will cause Q4 and Q12 to conduct and hence will reverse the current flow through the motor.

'''Note Do not apply a positive signal to both inputs at the same time.'''

Using this circuit it is possible to control the speed of the motors by pulsing the inputs (PWM Control).

From the Big Trak circuit it is not possible to determine the identities of transistors Q8 and Q10 as they are very small surface mount devices.

=== Scope Plots ===
Big Trak uses PWM control to accelerate the motors up to speed and also to slow them down when stopping. The scope plots below show the output from IC2 when Big Trak is programmed to move in a straight line then stop. The first plot shows the acceleratiom, the second the deceleration. The period of the pulses are 8ms.

[[File:accel.jpg|200px|Big Trak Motor Control - Acceleration]]
[[File:decel.jpg|200px|Big Trak Motor Control - Deceleration]]

=== Replacement Options ===
As the Big Trak circuit will eventually be removed it will be necessary to make a replacement motor control circuit. This web site [http://www.electronics-tutorials.ws/blog/h-bridge-motor-control.html] has some useful information and also suggests an H-Biridge motor control IC that could be used instead of discrete components. This is the National Semiconductors [http://www.ti.com/lit/ds/symlink/lmd18200.pdf LMD18200]. This is probably a bit of an overkill but it's a start.

#[http://www.sparkfun.com/products/9457 Motor Driver 1A Dual TB6612FNG]
#[http://www.active-robots.com/motor-driver-1a-dual-tb6612fng.html Motor Driver 1A Dual TB6612FNG UK source]

== Encoder Circuit ==
Big Trak has a simple encoder system for measuring how far it has travelled. They monitor the second stage gears which have a cut out in them. The circuit diagram for this is shown below. Not 100% sure this is correct (Needs checking).

To conserve power the circuit is only enabled when required. This is done using transistor Q1. The control line is connected to IC3.

[[File:encodercircuit.jpg|400px|Big Trak Encoder Circuit]]

== Connecting the Raspberry Pi to a Rev 1.0 BT Main board ==
Before the Big Trak circuit can be used by the Raspberry Pi it is necessary to remove IC2 and IC3 from the board. These are tricky to remove but so far the best approach is to use a heat gun to remove them. If you don't wan't to remove the IC's then the tracks could always be cut.

[[File:BigTrak2010Rev2MainBoardTop.JPG|200px|thumb|right|Big Trak main board Rev 2.0]]

Big Trak main board Rev 2.0 has a slightly different component idents and layout, however the locations to hack into are the same.
Alternatively, after removing the main IC daughter board it possible to use the pads in accordance with the [[Big_Trak_Circuits#Rev_2.0_IC_Pinouts | pinout]].

The image below has been annotated to show the points on the Big Trak board that need connecting to the Raspberry Pi.

[[File:014BigTrakBoardTop_Mods.jpg|500px|Big Trak Circuit]]

{| class="wikitable" style="text-align: center; width: 400px; height: 200px;"
|+
|-
! scope="col" | Number
! scope="col" | Description
|-
! scope="row" | 1 || Motor Left -ve PWM
|-
! scope="row" | 2 || Motor Left +ve PWM
|-
! scope="row" | 3 || Motor Right -ve PWM
|-
! scope="row" | 4 || Motor Right +ve PWM
|-
! scope="row" | 5 || Left Encoder Feedback
|-
! scope="row" | 6 || Right Encoder Feedback
|-
! scope="row" | 7 || Encoder Enable
|-
! scope="row" | 8 || Encoder Enable Over-ride
|-
! scope="row" | 9 || 3V3 Supply
|-
|}

If required the encoders on the Big Trak can be permanently enabled by connecting point 8 to the 3V3 supply at point 9.
== Cable restraint ==
The flat cable to the keyboard can be removed. The cable restraint can be reused for a ribbon that connects the BigTrak board to your Raspberry Pi. Reusing the cable restraint prevents strain on the solder joints, particularly when reassembling the completed project.

== References ==
#[http://www.alldatasheet.com/datasheet-pdf/pdf/419843/SECOS/D882S.html D882S Datasheet]
#[http://www.alldatasheet.com/datasheet-pdf/pdf/419598/SECOS/B772S.html B772S Datasheet]

Talk:Big Trak Circuits

2012-10-13T00:12:35Z

BillyBag2: Created page with "I [BillyBag2] have found the pin on the BigTrak rev 2 board that goes to the audio "amplifier" and speaker. I will try and add this detail and also work out if it accepts an anal..."

I [BillyBag2] have found the pin on the BigTrak rev 2 board that goes to the audio "amplifier" and speaker. I will try and add this detail and also work out if it accepts an analog or PMM signal from the Pi.