To supply a executable hardware design for Sub-Atlantic trial box utilizing PIC microprocessor with proper choice of PIC IC and constituents. Plan a robust and care free trial box with equal protection on telemetry PCB to be tested. Test or confirmation has to be easy to utilize with minimal user intervention and easy to read consequences. Hardware design will organize a starting point for package integrating.

Chapter 1: Introduction

For every ROV system, there is a complex circuitry of proctor and control in existent clip operation. This complex circuitry involves a combination of package and preciseness electronics and usually forms the bosom of the ROV. For Sub-Atlantic ROV, this proctor and control mechanism is in its telemetry system viz. PCB176-1 ( topside ) and 176-2 ( subsea ) . Some may merely name this the ROV accountant. Sing that this is an of import or instead critical constituent in a smooth operation of an ROV system, it is critical that these constituents are kept in serviceable status at all times. However holding said that, there is no kit or trial box available to the terminal users to verify the serviceableness of sub-Atlantic ROV telemetry system till day of the month. The lone manner that the terminal user is able to verify serviceableness of these boards is by trading PCB176-1 or PCB176-2 in a test and mistake method which is non ideal. Not being able to verify the serviceableness of these accountants may do unproductive and expensive down clip operations to ROV operators particularly so when ROV are chiefly used in seaward operation.

In admiting this demand in confirmation of its accountant, Sub-Atlantic intends to construct a trial box for this intent. This study forms the conceptual hardware design of this trial box.

Although Sub-Atlantic does hold an in house trial kit to verify its telemetry system/controller, this trial box has proven to be unequal and requires an experience technician to utilize. Sub-Atlantic in house trial box will be discussed further in chapter 2.

Aims

The aim of this undertaking is to supply a conceptual hardware design for Sub-Atlantic telemetry trial box. This will see the best attack and interface required. The design has to supply equal protection to the trial box for care free usage while executing all functional trials with minimum user attempt with easiness of construing consequences. Form the starting block for package design.

Sub-Atlantic Ltd

Sub-Atlantic was formed in 1997 in Aberdeen, Scotland. It started out as a little company fabricating little to medium size electric ROV ‘s, Hydraulic ROV pushers and subsea constituents. Today, Sub-Atlantic is an ISO 9001accrediated company and is a market leader in the design and maker of electric ROV ‘s. The new Mohican and Comanche are puting new criterions in electric ROV public presentation. The 3000 Volts, 400 Hertz transmittal system allows these vehicles to run over really long, but little diameter overseas telegrams. The Comanche has been supplied in a 6,000 meter / 20,000 pess constellation. Sub-Atlantic has besides late introduced their new SubCAN telemetry control system which is based on the new dsPIC microcontroller and COLDFIRE microprocessor with CAN coach communicating.

The Range of sub-Atlantic ROV ‘s are Navajo, Apache, Mohawk, Super Mohawk, Mohican and Comanche. All its ROV is controlled via its Telemetry system except for those with their new subCAN control system. Below is some of Sub-Atlantics ROV.

Chapter 2: Background

Sub-Atlantic Telemetry System

Above is Sub-Atlantic telemetry system used in all ROV vehicles except those runing under SubCAN control system. The scope of Sub-Atlantic ROV is Navajo, Apache, Mohawk, Super Mohawk, Mohican and Comanche. The above Telemetry has 8 parallel input and end product which can be set either uni-polar ( 0-5V ) or bipolar ( A± 5V ) . It besides has 16 TTL digital input and end product. As for communicating, it has a RS-485 and two RS-232 channels.

Two cards are used in a ROV control, an octangular sub-sea board ( PCB176-2 ) located in the ROV electronics lodging and a individual Euro-card format ( PCB176-1 ) used in either the PDU or Pilot remote accountant. Data is transmitted via an optically coupled RS-485 nexus between the two cards. Both cards operate in a master/slave relationship which is settable via nexus 20.

The top-end card ( PCB176-1 ) polls on a regular basis for information from the bottom-end ( PCB176-2 ) card. The maestro which is the top-side card includes the latest scenes for the slave end product in the canvass petition. When the slave receives the canvass petition it decodes the end product values passed from the maestro and so answers with its ain sample informations. A watchdog is used to supervise the exchange of day of the month. The microprocessor used in this system is the 8051 architecture produced by ATMEL and Philips. The processor besides communicates with a Programmable Logic Device ( PLD ) which provides 16 spots of digital end product informations. Logic choice of the ADC, DAC and multiplexer is besides done here.

This card forms the bosom and encephalons of the ROV system!

In house Test Box

The current trial box used in the workshop has a maestro connection, slave connection, exchange to toggle between digital channels, 8 viridity LED ‘s, 8 red LED ‘s, internal or external RS485 communicating switch, 2 of RS232 ports and a LCD panel to expose parallel end product. This box has so far proven sufficient but it requires a competent technician to decode the mistakes. Besides it requires an extra Personal computing machine to prove the functionality of RS232 nexus. Apart from that, the digital channel tested is merely the input from the maestro board to the end product of the slave board ; the LED ‘s are indicants of the slave digital end product. So in order to prove the maestro digital end product, the card has to be swapped between the maestro and break one’s back connection. Depending on the package used, sometimes merely by trading the cards is non possible therefore the demand to trade the IC1 between the cards but this may non work on all package versions. However, with this pattern, there is a possible that the IC ‘s are non swapped back after trial! Another drawback found is the linear channel does non hold the installation to change the linear signal. At the minute, confirmation is done by holding a 5V at each channel. This could take to a misunderstanding of the trial as if there is a stuck at high, it will go through the trial. The technician will non cognize be able to place this mistake.

Chapter 3: Design Approach

Approach

There are a few ways of carry throughing the above standards and the easiest is to merely utilize the “ difficult ” wiring method which is like the current box but with a few alterations. However to incorporate the RS-232 examiner and the ability to change the parallel signal will do the trial box excessively large. Second to construct the trial box for sale will turn out clip consuming and wasteful. This thought was rapidly dismiss.

The most likely method will be the usage of a microcontroller as it ‘s comparatively inexpensive and able to run into the full design demand. A microcontroller ( besides known as MCU or AµC ) is a computer-on-a-chip, incorporating a processor, memory, and input/output maps. It ‘s chiefly used is in embedded system. Microcontroller is merely a microprocessor with high integrating such as read-write memory for informations storage, read-only memory for plan storage, EEPROM for lasting informations storage, communications protocols, Analog to Digital convertors and input/output interfaces, in contrast to a all-purpose microprocessor ( merely like the normal Personal computer ) . Operating at clock velocities of a few KHz or more ( compared to modern twenty-four hours microprocessors ) , which is usually equal for typical applications. They consume comparatively small power ( miliwatts ) , and will by and large hold sleep map built in while waiting for a peripheral event such as a button imperativeness to wake them up once more to make something. Power ingestion in sleep manner is usually in nanowatts, doing them ideal for long permanent battery applications.

Microcontrollers

Microcontrollers are used widely in about every facet of our lives which we may non even gain. Microcontrollers are used in about all automatically controlled merchandises and devices, such as car engine control systems, distant controls, house white goods, office equipments, power tools, nomadic phones, modern twenty-four hours appliances and even toys! With changeless decrease in size, cost, and power ingestion compared to a design utilizing a separate microprocessor, memory, and input/output devices, makes microcontrollers a popular pick to interior decorators.

However the universe of microcontroller is turning quickly and invariably germinating with new devices means interior decorators are spoilt with picks. Common illustration of microcontrollers architectures are: Intel 8051, PIC, dsPIC, Coldfire, AVR and etc. Each microcontroller has its advantages and disadvantages with some for really specific utilizations. Therefore there is no such thing as the best microcontroller or most efficient microcontroller. Most design selects the usage of a peculiar microcontroller based on experience, handiness and resources that is already available.

As for the determination of which microcontroller to utilize for this undertaking was non hard because Sub-Atlantic started utilizing dsPIC and Coldfire for its new control system therefore it ‘s merely logical the design of this new trial box is base on PIC architecture as most of the resources are already available and to streamline our merchandise scope. Another advantage of utilizing PIC is the sum of resources available from the maker, Microchip and web forums.

PIC microcontroller is based on a modified Harvard RISC direction set. It has the advantage of a little direction set of 30 ( low terminal ) to 80 ( high terminal ) . Another advantage of PIC is that direction and informations are transferred on separate coachs which than reduces bottle cervix and reduces processing clip. Another chief advantage is migration between PICs is possible as its upward compatible. There many write up on the comparing between Intel 8051, PIC and AVR on the cyberspace with some supplying really strong disposition to a peculiar architecture. None nevertheless is able to convert which is the best. PIC has gained enormous popularity because of the broad forum support from professional and avocations likewise. There are inexpensive and easy available as good.

Development Tools

There are plentifulness of development board available in the cyberspace and from assorted makers. The most popular being Microchip ‘s ain PICDEM series and MPLAB in circuit debugger. Again this is up to personal penchant and options available. For Sub-Atlantic we decided on MikroElektronika EasyPIC5. This has a better options provided on a individual kit as compared to others and supports both a LCD and Graphical LCD with touch screen capableness and tonss of Input/Output switches with in circuit debugger and coder. The cost of this board is really competitory at merely ?120. It supports up to 40 pins PIC. Below is a image of MikroElektronika EasyPIC5.

Chapter 4: Design Specifications

Design Requirement

The new trial kit has to hold the undermentioned maps.

To prove all 16 digital end product without holding to trade cards.

To prove all 8 parallel end product without holding to trade cards and the ability to change the parallel input.

The ability to prove RS-232 without a demand for an external Personal computer.

The ability to place mistakes rapidly and accurately.

The new trial box has to be portable ( little ) , rugged and easy to utilize.

PIC IC Selection

For this undertaking, choice of PIC AµC is done via Microchip MAPS ( which stands for Microchip Advance Parts Selector ) merchandise choice tool. MAPS is micro chip ‘s new invention in merchandise choice which offers the user the pick of either offline and on-line choice. Microchip has divided their merchandise in three classs viz. Analog, Memory and Microcontroller. For this undertaking, we would be interested in the microcontroller subdivision. Once in the microcontroller page, choice is done by filtrating in the figure of I/O, figure of A/D required and etc. Below is a screenshot of Microchip MAPS

As the development kit that is purchased from MikroElektronika merely supports up to 40 pins, this will be the chief filter that has to be in at all times. Next will be the figure of USART required. From the design, we will necessitate a lower limit of 2 but holding 4 USART will be ideal. However after traveling through Microchip ‘s MAPS, no PIC matches the demand as most PIC within this series has 1 USART and a Master Synchronous Serial Port ( MSSP ) . Some french friess nevertheless has a combined USART or MSSP which is of no usage to this undertaking. In order to get the better of the deficiency of RS232, the usage of Maxim ‘s MAX1030 which is a Double RS232 to SPI convertor is used. The advantage of SPI is the ability to link in daisy wheel which so increases the sum of peripheral needed. Here, we will be utilizing another Maxim ‘s IC, MAX 3110 for the Analog to Digital convertor as the sum of Analog input on PIC18F4685 is limited to 13. MAX3110 has 16 A/D convertor which communicates via SPI. So in this instance we are able to spread out the parallel inputs to 32 ( 2 X MAX3110 ) or more with add-ons of MAX3110.

Another choice standard that is non critical to this undertaking but for future enlargement is the PIC selected to hold a CANBUS. This is because all new boards ‘ development in SUB-Atlantic has CANBUS capableness and if there is a demand this trial box can be integrated into the system.

As for the figure of I/O pins, it is best to merely choose the highest figure of I/O available. As this is a first undertaking it will be easier, for PCB layout design and adding any extra input or end product as the undertaking progresses. So after seting all the demands, we are down to 6 PICs. From the 6 PICs, PIC18F4685 has the largest figure of I/O, Page Memory and RAM. The monetary value difference between the 6 PICs are fringy ( less than ?5 ) and because this trial box is non traveling to be produce in 1000s, pricing is non a factor therefore the choice of PIC18F4685. PIC18F4685 Data sheet can be found at www.microchip.com

Chapter 5: Design

Design

The most of import factor in the design procedure is for the trial box to be rugged and dependable. With this in head, equal protection circuit are integrated in the design for care free operation.

The trial box will be connected via two 64 manner female blare connections to PCB 176-1 and PCB 176-2 which will be marked as TOPSIDE and SUBSEA severally. A block diagram of the connexions is shown on the nest page. From the diagram, the RS-485 Link is connected straight between PCB 176-1 and PCB 176-2 to set up telemetry communicating. There was n’t any ground to interfere with the existent RS485 nexus as we are merely involvement in verifying the digital, parallel and RS232 communicating. Another chief ground for non interfering with the RS485 nexus is that it would required extra package programming which is rather involved and with assorted version of package for different ROV, this would do synchronism for a “ cosmopolitan ” trial box excessively complex.

Because of the limited I/O channel, the debut of MAX 3110, a Dual UART to SPI IC from Maxim and MAX103, 16 channels A/D convertor is used. The advantage of these 2 MAX IC is that they both support SPI consecutive protocol. The use of MAX3110 is first-class as we are able to prove 2 RS232 channels at one time without holding a switch to toggle between channels. This is the same with parallel end product from the telemetry boards.

2 X 74HCT573

2 X 74HCT573

Soap 1030

Soap 3110

Soap 3110

2 X LM324

2 X LM324

SPI Serial

PWM Output

Digital Output

Port D

RD0, RD1, RD2, RD4, RD5, RD6, RD7

PIC18F4685

2 X16 LCD Display

Port C

CCP1

Port A

RA1

Port C

SDO, SDI, SCK

Port A

~SS

PCB176-1

PCB176-2

Digital In

Analogue In

Analogue Out

RS232-1 & A ; 2

Digital Out

Digital In

Analogue In

Analogue Out

Digital In

Digital Out

16 Ten Green LED

16 Ten Red LED

RS485

Telemetry Test Box

Datas Out

SW1

SW2

Port B

RB0

Port B

RB1

Digital Select

0V / 5V

Analog Select

0V / 2.5V /4.5V

Digital Output Verification

Confirmation of digital end products of PCB 176 is done via a fleeting switch ( to toggle between 0V and 5V ) which is so input to the AµC. The AµC will so give a digital end product which is so ganged to 74HCT573 ( an Octal D type transparent Latch ) which in so fed to the digital inputs of PCB176. There will be 16 LEDs for each PCB 176 to stand for each of the16 digital end products. The ground for the ganged input to PCB176 is because there is no manner verify the inputs therefore the ganged input. The toggling of 0V and 5V is to be able to verify that none of the end products are “ stuck at high ” or “ stuck at low ” . Below is a block diagram for Digital confirmation.

0V or 5V

Switch

AµC digital

I/O

2 X Octal Buffers

2 X Octal Buffers

PCB176-1

Digital Output

PCB176-2

Digital Output

PCB176-1 o/p via LEDs

PCB176-2 o/p via LEDs

Digital confirmation scheduling will be based on the flow chart below. The package will unclutter any checksum so checks the high/low choice switch which will be a digital input. If no choice is made, it will give a low end product ( 0V ) and return to start/clear cheque amount. If a high choice is made, it will give a high end product ( 5V ) and return to start/clear cheque amount.

Start

0V/5V

Choice

Digital Output set to high

Digital Output set to Moo

0

1

RS232 Verification

As already noted, there are two RS232 channel on Sub-Atlantic telemetry system. Confirmation is done by directing a twine from PCB176-1 and verified by PCB176-2 and so direct back to PCB176-1. The twine of informations can be either a phrase or an incremental sequence of figure. The twine that is received on PCB176-1 is so displayed on LCD. Block diagram as shown below.

RS232-2

RS232-1

RS232-1

PCB176-1

PCB176-1

RS485

AµC

RS232-2

MAX3110

MAX3110

SPI Serial

Liquid crystal display

Testing of RS232 channel is done via MAX 3110. MAX3110 is a SPI/microwire Compatible UART from Maxim/Dallas. MAX3110 has a double channel RS232 which converts the signal to SPI. The day of the month twine will so be displayed on the LCD. Below shows how the SPI connexion is made between the PIC18F4685, MAX3110 and MAX1030 utilizing daisy wheeled method.

PIC18F4685

MAX3110

SDO

Spacecraft clock time

Spacecraft clock time

Spacecraft clock time

Spacecraft clock time

~SS

~SS

~SS

~SS

MAX1030

MAX3110

SDI

SDI

SDI

SDI

SDO

SDO

SDO

Programing for RS232 confirmation is done by directing a twine of informations ( i.e. Testing of RSR232-1or an incremental sequence of figure ) and the receiving system compares the twine with the send informations and displays the receive twine on LCD. The same will be for RS232-2 with a twine of informations ( i.e. testing of RSR232-1or an incremental sequence of figure ) . The interface between MAX3110 and the AµC is via SPI. The AµC will move as maestro and the other SPI devices will be slave connected in daisy wheel. Flow chart for RS232 confirmation is as below.

Start

Initialise SPI

Initialise LCD

Send twine 1

Read Stringing 1

Display threading 1

Send Stringing 2

ad twine 2

Display threading 2

Analog Output Verification

Testing of the Analog channel will requires one 16 Channel A/D convertors with SPI consecutive end product. The usage of an A/D is because the parallel channel in the AµC is merely 13 channels. The A/D that we ‘ll be utilizing is MAX 1030 from Maxim/Dallas. This IC has a SPI consecutive communicating which is able to manage daisy wheel. The information from MAX 1030 is transferred to the AµC via SPI consecutive. Like the digital confirmation, there is no manner to verify parallel inputs ; therefore the parallel inputs to the telemetry will be ganged. Voltage choice is done via a switch to toggle between 0V, 2.5V and 4.5V. This is to imitate an parallel input. The end products from the telemetry boards will so be fed to a 16 channel A/D convertor. As the A/D convertor has an SPI consecutive port the consequences will be fed to the AµC and displayed on LCD. A block diagram demoing the parallel confirmation is shown below.

Liquid crystal display

Buffer Output

AµC

PWM O/P

SPI consecutive port

PWM O/P

PCB 176-1 parallel input

PCB 176-2 parallel input

PCB176-2 parallel end product

PCB176-2 parallel end product

Buffer Output

16Ch A/D convertor

Software programming for parallel confirmation will be in two parts, one to bring forth a PWM ( Pulse width Modulation ) selectable via a switch to toggle between 0V, 2.5V and 4.5V which are fed to the parallel inputs of both telemetry boards. The end products of these boards will be fed to a 16 Channel A/D convertor and communicates via SPI to the AµC the consequence is displayed on the LCD. Software scheduling is shown on the flow chart below. Flow chart on the right shows the end product of the AµC and on the left the input to the AµC.

Start

PWM end product 0V

PWM end product 2.5V

PWM end product 5V

Voltage Choice

Voltage Choice

Voltage Choice

0

0

0

1

1

Roentgen

1

Start

SPI Serial from MAX 1030

Initialise LCD

Display Analog Value

Microcontroller Port Mapping

Now that we have the all the confirmation construct in manus, we can than work out the finer inside informations on how the microcontroller will be wired up. The microcontroller that we will be utilizing is the 40 pins dip PIC18F4685 and the pins layout obtained from microchip informations sheet is as follows.

Description of the pin I/O is found in appendix under PIC18F4685 data sheet. Pins 35 and 36 will necessitate to be left unconnected which means digital I/O 2 and digital I/O 3 in port B ca n’t be used. This is pins are left for future enlargement for CANBus. Besides as we will be utilizing SPI, pins 7,18,23,24 rich person to be dedicated to that. For the minute, merely 3 digital I/O is required that is for digital confirmation end product, digital electromotive force select and linear electromotive force select. The latter two Acts of the Apostless as input I/O. We will besides necessitate 7 I/O to drive the LCD show. So in entire we will necessitate 10 I/O ports. A brief sum-up of the pins used is shown in the following page.

Summary of Pins used on PIC18F4685

AµC Pin No

Pin Labels

Connected to

Remarks

1

ICSP Connector

In Circuit Debugger

3

RA1

74HCT573

Ganged digital inputs

7

MAX 3110 & A ; MAX1030

Slave SPI select

11

VDD

Supply Voltage 5V

12

Volt

Supply Voltage 0V

13

OSC1

Crystal ( 20MHz )

External Crystal

14

OSC2

Crystal ( 20MHz )

External Crystal

17

CCP1

LM324

PWM end product

18

SCK

SPI Clock

Ganged to all MAX IC

19

RD0

Liquid crystal display

Read /write

20

RD1

Liquid crystal display

Chip Enable

21

RD2

Liquid crystal display

Roentgen

23

SDI

Soap 3110

On PCB176-2 side

24

SDO

Soap 1030

27

RD4

Liquid crystal display

Datas

28

RD5

Liquid crystal display

Datas

29

RD6

Liquid crystal display

Datas

30

RD7

Liquid crystal display

Datas

31

Volt

Supply Voltage 0V

32

VDD

Supply Voltage 5V

33

RB0

SW1

Digital 0V/5V

34

RB1

SW2

Analog 0V/ 2.5V/ 4.5V

39

PGC

ICSP Connector

In Circuit Debugger

40

PGD

ICSP Connector

In Circuit Debugger

Panels Layout

As this is an on-going undertaking, design may alter to accommodate parts handiness and PCB layout and size. The preliminary design of the trial box will be every bit close to the original design as possible. The first thing is to beginning the trial box itself. As it needs to be comparatively little, the box used will be from RS portion numbered RS505 820. Dimension of the box is 190 Ten 138 Ten 47. This box has an aluminum home base on its face, so doing holes and suiting a LCD will be much easier. With a detachable face the option of holding it silk showing is possible. The box is of ABS building so it ‘s rather robust. As for the connections to the PCBs, we will be utilizing ribbon overseas telegrams as it will be easy and speedy to assembly the 64 manner connections. RS portion figure for the connection is RS163 0905 and the thread overseas telegram is RS289 9997.

In the box, there will be a 24Volts and 5Volts unfastened instance PSU unit which powers the whole unit.

Below is a unsmooth lineation of the constituents placed on the box panel.

On/Off

Digital Voltage choice

Analog Voltage choice

16 X 3mm unit of ammunition RED LED

16 X 3mm unit of ammunition Green LED

PCB 176-1 Digital Output

PCB 176-2 Digital Output

Telemetry Test Box

LCD Display

Chapter 7: Decision

The usage of PIC18F4685 seems feasible but may turn out to be over eyeglasses. However, the following size down PIC is 28 pins which than is excessively little. So the 40 pins PIC will look to be the right microcontroller. Again the ground to alter to a different PIC will be the monetary value. For this application, memory required to run the plan will be minimal although this will necessitate to be proven. As for velocity of the microcontroller, this PIC is able to accomplish the soaps velocity of 40MHz. So the lone existent ground to alter the PIC will be monetary value but this would non be a factor as the monetary value difference for the PIC and the merchandising monetary value of the finish trial box will be negligible.

The following measure will be package development and it would be really likely to be written in C. Again this will necessitate a through research on the compiler usage. The plus point is the there are tonss of resources from the cyberspace on beginning codification illustration and tips and fast ones.

Mention

Sub-Atlantic ROV Manuals

hypertext transfer protocol: //en.wikipedia.org/wiki/Microcontroller

hypertext transfer protocol: //en.wikipedia.org/wiki/PIC_microcontroller

hypertext transfer protocol: //en.wikipedia.org/wiki/Intel_8051

hypertext transfer protocol: //www.mikroe.com/forum/

hypertext transfer protocol: //www.piclist.com/techref/piclist/index.htm

hypertext transfer protocol: //www.voti.nl/swp/

hypertext transfer protocol: //www.microchip.com/

hypertext transfer protocol: //www.maxim-ic.com/

hypertext transfer protocol: //www.intel.com/design/mcs51/index.htm

hypertext transfer protocol: //www.best-microcontroller.com