DLP-VLOG

DLP-VLOG
*LEAD-FREE*
VINCULUM-BASED TEMPERATURE / HUMIDITY /
VOLTAGE DATA LOGGER
FEATURES:
¾ Virtually Unlimited Data Storage Utilizing FTDI’s New Vinculum™ USB Host IC
¾ Data Logged to USB Flash Drive
¾ Low-Power Modes for Long Battery Life
¾ System Power via Two AA Batteries
¾ Lead-Free; RoHS Compliant
DEVELOPMENT KIT INCLUDES:
¾ DLP-VLOG Module
¾ C Source Code for the Microcontroller Firmware
¾ Windows Support Software for Real Time Clock Setup
¾ Windows Data Conversion Software
¾ C Compiler and Device Programmer/Debugger
2xAA
Batteries
DC-DC
5V
3.3V Reg
Temp/Humidity
Sensor
USB Flash
Drive
FTDI
Vinculum
VNC1A
PIC 16F88
Microcontroller
Real Time
Clock
2-Channel
Analog
Input
Buffer
0-30VDC In
Rev. 1.2 (July 2009)
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©DLP Design, Inc.
1.0 INTRODUCTION
The DLP-VLOG is intended as both a demonstration platform for the new Vinculum IC as well as a
learning tool. The Development Kit is designed to log temperature, humidity and voltage data to a
USB Flash drive. Using the Vinculum IC from FTDI, this system demonstrates how one can provide
virtually unlimited data storage for a small microcontroller.
This system can be beneficial to electronics enthusiasts with virtually any level of technical expertise.
Based on the Vinculum Host Controller IC and the Microchip PIC16F88 Microcontroller, the
DLP-VLOG can function as a digital design trainer, a microprocessor development system, or as a
rapid path to learning how to implement a USB Host Controller for interfacing a USB Flash drive to a
small microcontroller.
Programming headers on the board allow for firmware updates to both the microcontroller and the
Vinculum IC so that the board can be updated with additional features developed by the user as well
as firmware updates for the Vinculum.
A highly optimized C compiler from Custom Computer Services is provided with the kit that supports
the microcontroller firmware. Changes made to the firmware can be debugged and reprogrammed
into the microcontroller using the CCS ICD Programmer/Debugger module, which is also included
with the kit.
The sensor used in this design is the Senserion SHT11. While this sensor will acquire temperature
data in the range of –40 to 123.8°C (-40 to 255°F), it is recommended that you restrict exposure of the
module to the commercial temperature range of 0-70°C. The humidity range for the sensor is 0-100%
(non-condensing).
Refer to the datasheet for the SHT11 for detailed specifications.
2.0 DOCUMENTATION
The following items are available from the VLOG download page (http://www.dlpdesign.com/vdn9/):
•
An expanded version of this datasheet/manual
•
The electrical schematic in both PDF and Orcad formats
•
Microcontroller firmware source code
•
The modified version of the DS1302.c source code file
•
A Windows utility for creating the Real Time Clock setup file
•
A Windows utility for converting DLP-VLOG output data to floating point values
Rev. 1.2 (July 2009)
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©DLP Design, Inc.
3.0 FLOW DIAGRAMS
3.1 STARTUP SEQUENCE
Power Up / Reset
Flash LEDs
Power Up and
Synchronize with
Vinculum
#use rs232(baud=9600, xmit=PIN_B5, rcv=PIN_B2, FORCE_SW)
//send 'E' until echoed back
putc('E');
putc(0x0D);
//send 'e' once
putc('e');
putc(0x0D);
putc(0x0D);
// "D:\>" or "No Disk" returned
USB Flash
Drive Present
?
N
Power Off Vinculum
---------------------------Sleep 10 Seconds
(100uA)
Y
On power up or after a device reset, the firmware needs to know if a USB Flash drive is connected to
the board. In order to do this, the microcontroller must first synchronize with the Vinculum. This is
accomplished by sending an upper-case ‘E’ to the Vinculum via the serial interface until it is returned
by the Vinculum. Once the ‘E’ is returned, a lower-case ‘e’ is sent to complete the process.
Next, the firmware sends the carriage return control code 0xD. The Vinculum will respond with either
“D:\>” indicating that there is a Flash drive connected and ready or “No Disk”, which indicates that no
drive is connected.
If no drive is found, then the firmware remains in a loop waiting for a drive to be connected so that
data can be saved. While the system waits for a drive, it will spend most of its time sleeping with the
Vinculum powered off to conserve battery power.
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©DLP Design, Inc.
3.2 REAL TIME CLOCK SETUP
printf("DIR timeset.dat");
putc(0x0D);
"Command Failed" or "TIMESET.DAT" returned
Real
Time Clock Setup
File Found
?
N
Proceed To Main Loop
Y
Read File And Write
Data To Real Time
Clock
printf("RD timeset.dat");
putc(0x0D);
//datafile contents returned
Proceed To Main Loop
Once a Flash drive has been connected to the system, the next step is to determine whether the user
has placed a setup file for the Real Time Clock on the Flash drive. If the file is present, it is read from
the drive, the data is written to the Real Time Clock, and then the file is deleted so as to prevent the
time data from being overwritten in the Real Time Clock the next time the module is reset.
Rev. 1.2 (July 2009)
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©DLP Design, Inc.
3.3 MAIN LOOP
Power Down Vinculum
And Sleep For 10
Seconds
------------------------Wake And Read Temp,
Humidity and Voltages
----------------------Save To Arrays (RAM)
**
One
Minute Interval
(Seconds = 50)
?
printf("CLF data.dat");
putc(0x0D);
Write Data To
File
printf("WRF ");
putc(0x0);
putc(0x0);
putc(0x01);
putc(0x08);
putc(0x0D);
printf("%ld\t", VDATA);
...Repeat For All Data...
putc(0x0D);
Open Data File
printf("OPW data.dat");
N
Y
Power Up &
Synchronize With
Vinculum
USB
Flash Drive
Present
?
Close Data File
Y
N
Reset Microcontroller
** Wakes at Seconds = 00, 10, 20, 30, 40, and 50
Once a Flash drive is connected and the Real Time Clock is set with the current time, the main loop
can begin taking readings. Again, the system remains in sleep mode between readings to conserve
power.
The microcontroller comes out of sleep mode about once every 600mS to read the Real Time Clock
and see if it is time to wake up. If a new ten-second interval has begun, then all readings are taken
Rev. 1.2 (July 2009)
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and stored to microcontroller RAM in raw form as A/D counts. If the Real Time Clock indicates the
end of a one-minute period, then the data is written to the Flash drive.
If the Flash drive is not present, then the user has removed it for data analysis and the microcontroller
simply resets itself to restart the process at the end of the one-minute interval.
Note that neither removing the Flash drive nor resetting the microcontroller via the reset button will
erase the time in the Real Time Clock. Removing power from the module is the only way to erase the
current time.
4.0 CIRCUIT DESCRIPTION
4.1 CURRENT MONITOR PORT
Great care has been taken in the design of this system to ensure that battery power is conserved
wherever possible. When no Flash drive is connected and the system is powered and waiting for the
drive from the user, it remains in sleep mode. The system also stays in sleep mode between
readings. While in sleep mode, the current draw from the batteries is approximately 100uA.
The 2xAA battery pack is mounted to the bottom of the PCB. Power enters the PCB from the battery
pack and immediately connects to R10; a zero-Ohm resistor. To monitor the current draw from the
batteries, remove R10 from the board and connect a current meter in series at JP1.
4.2 DC-DC CONVERTER
U3 is a synchronous boost converter that will convert the 3 volts from the batteries to regulated 5-volt
power. This device was chosen in part due its low power consumption. When the DLP-VLOG is in
sleep mode and only drawing 100uA from the batteries, U3 is only consuming 25uA itself.
4.3 REAL TIME CLOCK
U7 is the Real Time Clock. Three I/O port pins are required for communication with the microcontroller. Once the time and date are written to the registers in the IC, it will keep the correct time so
long as power is applied.
4.4 SENSOR
U1 is the temperature and humidity sensor. Only two I/O port pins are required for communication
with the microcontroller. The data I/O line on the Real Time Clock and the data line for the sensor
both share a port pin on the microcontroller (DATA/PGC).
4.5 MICROCONTROLLER CLOCK
U4 is a Microchip PIC16F88 Microcontroller. Since all communication with the devices on the board
are either asynchronous or at 9600 baud, no crystal or ceramic resonator is required to clock the
microcontroller. Instead, its internal oscillator is run at 8MHz.
Rev. 1.2 (July 2009)
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©DLP Design, Inc.
4.6 VINCULUM POWER SOURCE
Power for the Vinculum and Flash drive is controlled by the microcontroller via Q1. At the one-minute
interval, the microcontroller pulls VPWR low to turn on Q1 and check for the presence of the Flash
drive. This action supplies 5-volt power to the Flash drive and 3.3-volt power to the Vinculum (via the
U5 regulator).
4.7 PROGRAMMING INTERFACES
Firmware is written to the program memory in the microcontroller via the CCS ICD Programmer/
Debugger and IDE software. A small adapter PCB is provided that connects to both the 5-pin header
(H1) on the DLP-VLOG and the modular cable connected to the ICD.
Should the firmware in the Vinculum need to be updated, a 6-pin header (H2) is provided for
connection to the TTL-232R 3.3V USB-to-serial cable. This cable is available for purchase from
Mouser Electronics under part number TTL-232R-3V3, or from the FTDI on-line store. Be sure to use
the 3.3 volt version of this cable. The Windows software that performs this programming process is
available for download from the Vinculum website (http://www.vinculum.com/).
To update the Vinculum’s firmware, start by removing the batteries from the battery holder. Place a
shorting jumper across JP3 (MCLR) to hold the microcontroller in the reset state, and another shorting
jumper across PROG# and GND at JP2. Then connect the TTL-232R cable to header H2 with the
black wire going to pin 1 of the header. Finally, run the VPROG.exe utility to erase and reprogram the
Vinculum.
4.8 ANALOG BUFFERS
Analog voltages can be measured on the CH1 and CH2 inputs. Voltages present at these inputs are
first divided by R11, R12, R16 and R17 to provide an input range of 0-30 volts, and then buffered by
U8, which has been configured for unity gain.
5.0 FIRMWARE DESCRIPTION
This section will only cover items that some developers may find confusing. Questions that arise from
the source code listing that are not covered here should be directed to [email protected]
5.1 INTERNAL CLOCK
As mentioned earlier, since the serial interface to the Vinculum runs at 9600 baud, the internal
oscillator in the PIC 16F88 will work just fine for the system clock source. The internal oscillator is
enabled and selected via the CONFIG register when firmware is programmed into the microcontroller.
The source code line “#use delay(clock=8000000,restart_wdt)” tells the compiler the speed at
which the micro is running and enables use of the delay functions.
5.2 SERIAL PORT SETUP
Rev. 1.2 (July 2009)
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©DLP Design, Inc.
The PIC16F88 Microcontroller has an on-chip UART that can be utilized for communication with the
Vinculum. Please note that while the UART has interrupt capability, interrupts were not used for this
project in an attempt to make the code easier to understand.
The “#use RS232" pre-processor directive is shown but not called, so the Vinculum can remain
powered off in low-power mode. The "Force Software" parameter will cause software serial I/O
routines to be generated even though the UART pins on the micro are specified.
As soon as the #use RS232 directive is issued, the TX line will be taken high to the idle state. If this
line is high while the MOSFET is off and no power is applied to the Vinculum, there will be current
draw into the Vinculum via the TX line through the protection diodes.
5.3 CONSTANTS
A few constants are defined towards the top of the code listing; for example, #define S1 "OPW
data.dat". This was done as opposed to using the SPRINTF or PRINTF commands so as to save
program memory.
6.0 REAL TIME CLOCK UTILITY
At power up, the data registers in the Real Time Clock IC contain invalid time and date data. The
correct date and time must be written to these registers in order for valid time data to be logged to the
data file.
Setting the date and time in the Real Time Clock is accomplished by running the software utility
”SetupFileGen.exe” that is located on the Flash drive supplied with the kit. When run, this program
creates a binary file containing both date and time information. You can simply copy the binary file to
the root folder in the Flash drive, and when the Flash drive is reconnected to the DLP-VLOG module,
the Real Time Clock will be updated with the correct time.
You will note that there is a several-second delay from when the reset button on the DLP-VLOG is
pressed to when the data is actually read and stored into the Real Time Clock.
7.0 DATA CONVERSION UTILITY
In an effort to conserve program memory in the microcontroller, no floating-point calculations are
performed. All temperature, humidity and voltage data is written to the Flash drive in raw form as A/D
counts.
The software utility “VLOG File Convert.exe” is provided to convert the raw data file to usable floatingpoint data. To utilize this, simply run the application, select the file to be converted, click on Convert &
Save and select a location for the output file.
The utility will convert the raw data from this: 08/26/06 15:26:00 6705 1091 0819 0226 0552
To this: 08/26/06 15:26:00 27.38 84.14 37.1 26.59 12.15 2.661
Rev. 1.2 (July 2009)
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©DLP Design, Inc.
The nine data elements produced are as follows:
•
•
•
•
•
•
•
•
Date
Time
Degrees C
Degrees F
Humidity %
Voltage CH1
Voltage CH2
Voltage Battery
8.0 DISCLAMER
©DLP Design, Inc., 2006
Neither the whole nor any part of the information contained herein nor the product described in this
datasheet may be adapted or reproduced in any material or electronic form without the prior written
consent of the copyright holder.
This product and its documentation are supplied on an as-is basis, and no warranty as to their
suitability for any particular purpose is either made or implied. DLP Design will not accept any claim
for damages whatsoever arising as a result of the use or failure of this product. Your statutory rights
are not affected.
This product or any variant of it is not intended for use in any medical appliance, device, or system in
which the failure of the product might reasonably be expected to result in personal injury.
This document provides preliminary information that may be subject to change without notice.
9.0 CONTACT INFORMATION
DLP Design, Inc.
1605 Roma Lane
Allen, TX 75013
Phone:
Fax:
Email:
Internet:
469-964-8027
415-901-4859
[email protected]
http://www.dlpdesign.com
Rev. 1.2 (July 2009)
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©DLP Design, Inc.