PV WatchdogWeb-Enabled Photovoltaic System Monitor

Art Barnes

Austin Fisher

Ryan Mann

Josh Stone

PV WatchdogMission Statement

•To construct a photovoltaic monitor that is affordable for small photovoltaic installations. It will be capable of uploading system information to the web. The purpose of the system is to further awareness, aid in implementation and function as a diagnostic utility.

PV WatchdogBaseline vs. Desired functionality

Above the Line• Read from serial port and download code from serial• Sensor electronics integrated into module• Download new OS• Modem Communication

THE LINE!!

Below the Line• Download code from the web page• Ethernet Communication• Event Logging

PV WatchdogParts and Software Requirements

Hardware– Microcontroller– External Components– Sensors

PC Software– Monitor serial port to read bytes and write to data file– Format data file into web page– Upload OS and or configuration data via serial port

PV Monitor Software– Read sensor information through A/D– Pre-process data– Send data readings over serial– Monitor serial port for updates from server

PV WatchdogBlock Diagram

System Bus ADDR[16] DATA[8]

68HC11

Xilinx 4005E

ROMRAM

A/DConverter

LCD Keypad/LEDs

Module Backplane

SensorModule

SensorModule

UART

SPI

MUX

CS CS CS, OE, W E CS, OE

EN

ENCS CS

EN

DIPSettings

DIPSettings

SensorOutput

SensorOutput

OEW E

SensorOutput

PV WatchdogHardware : Micro-controller : Why 68HC11E

Why Motorola 68HC11E

– low power consumption (sleep mode)

– wake on interrupt

– watchdog timer– ease of

availability and price

– DIP package for mounting ease

– Built-in SPI interface

– Built-in RAM/EPROM

System Bus ADDR[16] DATA[8]

68HC11

Xilinx 4005E

RO MRAM

A/DConverter

LCD Keypad/LEDs

Module Backplane

SensorModule

SensorModule

UART

SPI

MUX

CS CS CS, O E, W E CS, O E

EN

ENCS CS

EN

DIPSettings

DIPSettings

SensorOutput

SensorOutput

OEW E

SensorOutput

PV WatchdogHardware : Micro-controller : Features/Limitations

Features/Limitations– Low order address lines

and data lines are multiplexed, requiring external latches

– Must use wait mode with higher current drain in order to use internal timers to wake up

– 8-bit resolution offered by internal A/D is insufficient, requiring external A/D

– SPI interface specifies Enable pin, but selection logic is not included, requiring an FPGA

PV WatchdogHardware : Memory

•0000 – 01FF Internal RAM

•0200 – 03FF Sensor Config.

•1000 – 103F Register Block

•6000 – 7FFF External RAM

•8000 – FFFF External EPROM

•B600 – 87FF Internal EEPROM ExternalEPROM

InternalEEPROM

SensorConfiguration

0000

200

3FF

6000

7FFF8000

FFFF

External RAM

0000

01FF

InternalRAM

1000

103F

RegisterB lock

B 600

B 7FF

FFC0

FFFF

InterruptVectors

PV WatchdogHardware : FPGA

Xilinx 4005E takes care of ‘chip selects’ and ‘enables’

System Bus ADDR[16] DATA[8]

68HC11

Xilinx 4005E

ROMRAM

A/DConverter

LCD Keypad/LEDs

Module Backplane

SensorModule

SensorModule

UART

SPI

MUX

CS CS CS, OE, W E CS, OE

EN

ENCS CS

EN

DIPSettings

DIPSettings

SensorOutput

SensorOutput

OEW E

SensorOutput

PV WatchdogHardware : FPGA

FPGA uses simple combinational logic to perform bus

selection based on address lines

PV WatchdogHardware : FPGA

PV WatchdogHardware : A/D Converter and Multiplexer

Use 12-bit single channel A/D converter 16 inputs are selected using a 16-1 analog multiplexer Converter talks with microcontroller over the SPI

interface Converter has low power consumption when not

enabledSystem Bus ADDR[16] DATA[8]

68HC11

Xilinx 4005E

ROMRAM

A/DConverter

LCD Keypad/LEDs

Module Backplane

SensorModule

SensorModule

UART

SPI

MUX

CS CS CS, OE, W E CS, OE

EN

ENCS CS

EN

DIPSettings

DIPSettings

SensorOutput

SensorOutput

OEW E

SensorOutput

PV WatchdogHardware : A/D Converter and Multiplexer

AnalogMultiplexer

A3

A2

A1

A0

SensorSignals

A/DConverter

PV WatchdogHardware : Board Schematic

PV WatchdogHardware : Sensors

Sensors encapsulated into modular package

– Analog level conversion and impedance matchingcircuitry

– Sensor type and configuration set using on-board DIP switches

System Bus ADDR[16] DATA[8]

68HC11

Xilinx 4005E

ROMRAM

A/DConverter

LCD Keypad/LEDs

Module Backplane

SensorModule

SensorModule

UART

SPI

MUX

CS CS CS, OE, W E CS, OE

EN

ENCS CS

EN

DIPSettings

DIPSettings

SensorOutput

SensorOutput

OEW E

SensorOutput

Sensor Types– Insolation Sensor– DC Voltage Sensor– DC Current Sensors– Temperature Sensors– AC Voltage Sensor– AC Current Sensor

PV WatchdogHardware : Sensors : Sensor Module

Consists of setting switch logic and analog conversion circuitry

Analog circuitry is specific to the type of sensor the module is intended to be used for

Sensor

Sensor connection:power, ground,analog output (sensorspecific)

D IPswitchsettingsto databus

ENablefromXilinx4005E

ScaledAnalogOut

Config Switchesand Logic

AnalogConversion

C ircuitry

S e ns o r B lo c k D iag ram

Sensor ScaleSettings

PV WatchdogHardware : Sensors : Sensor Module Settings

B uffe r

S IP P u ll-U p E NTo X ilinx

4005E fo rC h ip S e l

D ataB us

V +

D IP S w itches

M odule C onfiguration Use DIP switches

on the sensor module to identify sensor type and port number of temperature compensation module

Enable pin of Buffer is used for chip select, connected to Xilinx 4005E chip select logic

PV WatchdogModem Communication

Still want to add this feature Optional to system functionality

PV Monitoring

System

Modem

PV WatchdogSoftware : Monitor OS

S y s te mD ia g n o s tic s

B o o t U p

S e n s o rC a lib r a tio n

D ataP ro c e s s ing

T rans m it toS e rve r

S le e p

D ataC o lle c tio n

R e m o teC o n fig u r a tio n

PV WatchdogSoftware : Host PC

Master Control Program (MCP) polls the serial port and writes the bytes read to a data file

MCP can send email to administrator if it detects erroneous readings

MCP can log errors for diagnostic purposes MCP can wake up PV Monitor from sleep through the

68HC11’s interrupt-on-serial capability to change settings via serial port

PV WatchdogSoftware : Webpage

Simple, easy to read table layout

PV System MonitorCurrent Statistics        

Panel Voltage (V)

Panel Temp(degrees C)

Panel Current (A)

Power Supplied(W)

Battery Voltage(V)

123.45 123.45 123.45 123.45 123.45

123.45 123.45 123.45 123.45 123.45

123.45 123.45 123.45 123.45 123.45

Display One HourHistory

Display 24 HourHistory

Display One WeekHistory

Display One MonthHistory

PV WatchdogParts Listing

Motorola 68HC11E1 Current Sensors (CSLA2CD)

Discrete Components

Xilinx 4005E Buffers (74HC241, 74HC245)

Plugs & Jacks

Discrete Logic (7400, 7414)

LCD Display Cabling

Sockets & Headers Clock (DOC-20CF) Switches/Buttons

2 EPROM (AM27C256) Temp. Sensors Enclosures

RAM (HM6264P) Indicator LEDs

A/D Converter (MAX189AEPA)

Insol. Sensor

(Si-04-T)

Analog Mux (DG406DJ) Latch (74BCT373)

UART (MAX3110ECNI) Power Bus

PV WatchdogParts Cost

•Xilinx FPGA $26.65•Maxim A / D $6.95•HC11 Microcontroller $5.12•Maxim UART/RS232 $4.73•Maxim Analog Mux $3.48•AMD 32k EPROM $3.44•8k RAM $3.42•Clock $1.21•Discrete Logic, < $1 each Buffers Latches•Sockets, etc… $40•Prototype board $35•LCD Display $25

Estimated Total $165

PV WatchdogCurrently….

What Works:

- Program can be burned onto EPROM and successfully run

What We Are Working On:

- The FPGA is indicating a frame fault as it receives chip select data from the second EPROM

We are currently in the debugging process

PV WatchdogSchedule : Milestones

Milestone 1: Nov 7– Load program via serial connection– Implement Sensors– Design sensor interfaces– Setup configuration data

Milestone 2: Nov 21– Implement Flash memory– Setup web interfaces– Be able to upload data to server

PV WatchdogSchedule : Comprehensive

PV WatchdogConclusion

Intentions before expo

- complete “above the line” items

- Provide full documentation on the project

- Provide easy to use, brief manual

- Prepare system for delivery to the sponsor