Name of item | Robostix |
---|---|
Description of purpose | This expansion board has eight ADC channels which are used to obtain sensor measurements. It also has a number of IO ports that are used to switch various parts of the device On/Off. These include LEDs, sensors and the VDIP(usb host) module. For more details on Robostix see section 3.10.1. |
Source of input | Robostix receives sensor measurements on its ADC channels(F ports). For more details see section 3.10.2 |
Valid range, accuracy, and/or tolerance | Robostix is capable of producing a 10-bit resolution digital output from its ADC channels. |
Relationships to other inputs/outputs | Robostix is connected to Gumstix(the main processing module) via a serial port(Robostix' UART0 to Gumstix' STUART). It is through this serial port that Gumstix and Robostix can communicate and exchange data. Robostix must wait for Gumstix' instruction to start polling the sensors, which must be done through the serial port and then sensor readings will be returned via the same serial port. |
Name of item | Sensor board |
---|---|
Description of purpose | This board containes the four sensors which measure pollution. These include Carbon Dioxide, Carbon Monoxide, Organic Solvent Vapour and an acoustic sensor. This board provides the main source of input for this application. For more details on the board and its sensors refer to section 3.6 |
Source of input | This board is connected to the Robostix via Robostix IO pins. The exact pin assignments are explained in section 3.10.2. |
Valid range, accuracy, and/or tolerance | The values received from the sensors must be scaled between one and ten depending on the intensity of the measurement. |
Units of measure | The values received from the sensors must be graded between one and ten depending on the intensity of the measurement for displaying on the LED boards and for a geo-tagged view. However the full values received from the ADC must be logged and available for inspection. |
Timing | The sensors should be polled at three(preferably less) seconds intervals. All sensors apart from the Carbon Monoxide sensor do not have preheating periods, i.e. they provide a continoues stream of measurement. However for the CO sensor there is particular heating cycle that must be followed for optimum results. This cycle is explained in section 3.6.3. |
Relationships to other inputs/outputs | The measurement retrieved from each sensor on the sensor board must be appropriately scaled, packaged and sent to the LED board. The LED boards are connected to Robostix via its UART1 serial port. |
Name of item | Viculum VDIP(USB Host) |
---|---|
Description of purpose | This serial to usb converter module provides the platform with a a usb host which will be used to store the collected data onto a usb flash memory. So that users can easily upload the data to an online geo-centric service.s |
Timing | Once a usb flash memory is detected, logging of data must be done to a file on the flash memory as well as to the Gumstix' permanent storage. The steps involved including those from the user's perspective are shown in figure 4.2. |
Relationships to other inputs/outputs | This device shares the serial port(FFUART) of the Gumstix which is also used for connecting to Gumstix and opening a terminal. For more details on using the shared serial port see section 3.10.2. |
Data formats | The formatted data must be the same as that of the logs. |
Command formats | For a complete set of commands to be used with this module view its documentation[33]. |
Name of item | LED Boards |
---|---|
Description of purpose | There are four LED boards that host ten LEDs each. Every board corresponds to a single sensor and it contains ten LEDs. The purpose of these LEDs are to display the sensor reading in a scaled version of the measurements from one to ten. More details on this board is available in section 3.6.5. |
Source of input | The input received from the sensor boards by Robostix must be scaled and packaged according to the command format described in table 4.5 and sent via Robostix UART1 serial port. |
Valid range, accuracy, and/or tolerance | Each set of LEDs contains ten LEDs which are categorized as the
following:
|
Units of measure | The sensor measurements should be scaled from one to ten to accomodate the LEDs available on this board. |
Timing | The frequency of updating the state of these LEDs should be equivalant to that of the sensor polling iteration. |
Relationships to other inputs/outputs | Each set of LEDs is uniquely identified with an address. This address
is assigned by physically changing the location of jumpers on each
board. The addressing scheme is as follows:
|
Command formats | The necessary commands for switching the LEDs On/Off is outlines in table 4.5. |
Hex | Dec | ASCII | Description | Transmission |
---|---|---|---|---|
Order | ||||
0x02 | 2 | STX | Start of message character (Start of TeXt) | 1 |
0x08 | 8 | ... | Number of bytes in message core (Message size) It is the binary number of bytes contained between the ``start of core message'' and the ``end of core message''. In this case, 8 | 2 |
0xB1 | 177 | ... | Checksum; Sum of decimal byte values Modules 256.
|
3 |
--- START of CORE message --- | ||||
0x30 0x31 | 48 49 | 0 1 | Board address, represented in two bytes. Most Significant Nibble first, Least Significant Nibble second. | 4 5 |
0x35 | 53 | 5 | Command 5 to be executed | 6 |
0x31 0x31 0x31 0x31 | 49 49 49 49 | 1 1 1 1 | LEDs to be turned on. This has now become the binary description of the outputs. A bit cleared to zero turns the led on, a bit set to one turns it off. For example, if all leds are to be on, a value of 0000 (48 48 48 48) must be sent. If only the first two leds will light, then the value 03FC (48 51 70 67) must be sent. The blue led is the LS bit, the third red led is the MS bit. | 7 8 9 10 |
0x57 | 87 | W | A ``W'' (87) will indicate a write operation. (Capital letter W) | 11 |
--- END of CORE message --- | ||||
0x03 | 3 | ETX | End of message character (End of TeXt ) | 12 |
Jenson Taylor 2008-01-25