Off-Road Navigation with GPS Fugawi Global Navigator 3.3.1(7)
By admin | May 15, 2007
On the Water
Fugawi also sells Marine ENC for marine navigation. The package provides a complete set of Navionics or NOAA charts, including depth soundings, navigational aids, hazards, restricted zones, maritime place names and landmarks. The charts are available for all major waterways throughout North America, South America, Central America & the Caribbean, Europe, Africa Oceania and Asia.
On Land
If you know where you are going and the steps along the way, you can create a route consisting of a number of waypoints, then have Global Navigator direct you along the route, from waypoint to waypoint. Waypoints are created by tapping on the map at the point where you want to stop or change direction. Think of them as rest stops at the end of each leg of a journey.
Figure 12: Editing a waypoint after it’s created by tapping on the map.
Figure 13: By tapping the Edit Location button, you can provide more precise locating info (e.g. if you have exact coordinates).
Alternately, you can use these screens to create waypoints anywhere, as long as you know the coordinates.
To create a route, you specify one of the waypoints as the start and add waypoints until you identify the last one as the end of the route.
Figure 14: Naming a new route.
…to be continued…
Source: pocketpcthoughts.com
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Off-Road Navigation with GPS Fugawi Global Navigator 3.3.1(6)
By admin | May 15, 2007
Figure 10: An example track following along a street.
Then, once you’ve gone as far as you want, you can ask Global Navigator to run through through the route backwards and voila, you’re back at your starting point 
On the Road
The Canada Data Pack which comes with the software includes a Streets map, which can be used separately or as an overlay on any other map on the PC version. For the PPC version, it can only be loaded as a standalone map. Unfortunately, it was almost 10 years old so it had limited use in driving around in the city. I contacted Northstar, and no more recent version is available. There are some major roads shown on the topographic maps, but none are named or ‘bounded’. Street maps are available, I believe, for most major cities in the US and Europe as well, but be sure to check the date of issue/update.
Figure 11: An example shot of the Canada Streets overlay map.
As noted before, the street map overlay can’t be used to ‘route’ between locations since the software is not set up to recognize directions, addresses, etc. I did, however, find the positioning on the maps to be fairly accurate (tested at various street corners and at known topographic locations) which is crucial for these applications.
…to be continued…
Source: pocketpcthoughts.com
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Off-Road Navigation with GPS Fugawi Global Navigator 3.3.1(5)
By admin | May 15, 2007
Be careful how much you zoom in, however, since the maps are raster versions and if you get in too close, they will become pixelized beyond usefulness.
Figure 8: Excessive zooming in can render the map useless, since the graphics are not ’scaled’ but simply bitmap pictures of the original map.
The top left of the screen provides information on current speed and heading. In the right top is the current map scale, an indicator of whether the GPS unit has a ‘fix’ yet, and whether the GPS port is open (the P in a circle in the top right). Along the bottom is the menu system, then icons for toggling centering of the map on the current GPS position on and off, accessing the GPS information screens, and turning Tracking on and off.
The PDA version of the application basically provides the ability to track current location, mark waypoints, create a route of waypoints, and follow a route. You can also download routes and waypoints from those created/managed on the PC version None of the fun stuff like 3-D rendering and flythough based on elevation data is available.
The main difference between this and a road-based GPS application is that you really can’t ask GN “How do I get there?” because it will simply draw a straight line between you and destination, regardless of the terrain. Even using the street map overlay, Global Navigator is unaware of the use of streets as preferred routes for travel.
This application is most useful for back-tracking to the starting point when out on a hike (using the tracking function) or following a route predefined by you or supplied by others. The tracking function allows the application to mark your route as you travel, by recording your current position at regular intervals as you hike (or ride) along.
Figure 9: Setting up how GN tracks your progress.
…to be continued…
Source: pocketpcthoughts.com
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Off-Road Navigation with GPS Fugawi Global Navigator 3.3.1(4)
By admin | May 14, 2007
Fugawi on the PPC
Once you have some maps downloaded to your PPC, you’re ready to roll. As mentioned earlier, functionality on the PPC is limited to a subset of the PC-based version.
Figure 5: Main screen of Global Navigator with a local topographic map loaded.
As you can see from the screenshot above, the interface is built on the PPC2002/PC2003 o/s style, with most of the functionality built into the menu options at the bottom of the screen. From the File menu, the Maps/Open function provides a list of maps available for loading.
Figure 6: List of maps available in both program and storage memory. Unfortunately, only one can be loaded at a time, and there is no ‘automatic’ loading of the adjacent map once you hit the map boundary.
Moving around on the map is accomplished by tapping and dragging in the opposite direction to where you want to see – much like sliding a paper map under a glass viewing window. (I know, it sounds weird, but it’s quite intuitive, actually.) Zooming in or out of the map is accomplished using the top or bottom buttons (or up/down if it’s a joystick) of the PPC’s D-pad.
Figure 7: Depiction of the special functions of the D-pad keys when in Fugawi Global Navigator (from the Help file).
…to be continued…
Source: pocketpcthoughts.com
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Off-Road Navigation with GPS Fugawi Global Navigator 3.3.1(3)
By admin | May 14, 2007
Installing Maps
Unfortunately, installing maps to the PPC is a little cumbersome, since, again, they must be installed from the PC-based program. Northstar, the vendor/manufacturer in Canada, provides complete coverage of Canada using NRC maps at 1:250,000 (for an entire province) and 1:50,000 for specific sections. 1:50,000 is OK for longer hikes or bike rides where you’re covering tens of miles in a day, but it would be better to have something like 1:20,000 for more in-depth detail at a local level.
To transfer a map to the PPC, you need to bring it up on the PC, select an area to be transferred, zoom into an portion of the selected area to set the level of detail desired, then ‘prepare’ the map for the PDA. Preparation of a map basically consists of rasterizing the selected area of the map (i.e. creating a bitmap image) at the detail shown by the current zoom level. Depending upon the size of area selected and the zoom level, this preparation can take 5 to 10 minutes. It is possible to rasterize the entire map, but this would take longer and could require considerable storage space.
The PC version of Fugawi Global Navigator also supports overlaying of maps, such as placing the Street map over the topographic, to produce a pretty complete view of the terrain around the streets. Unfortunately, the PDA preparation routine only works with the base map selected, so you only get the topographic in the final PDA-ready image – not the streets.
Once the preparation is complete, you then select another function in the PC version to ‘manage’ the maps located on the PPC. This includes transferring from PC to PPC, deleting from the PPC main memory or storage cards, etc. Prepared maps are found on the ‘Exported Maps’ tab – which is not well explained in the documentation.
Figure 4: The Data Export screen on the PC version of Global Navigator.
Transfer occurs through the ActiveSync connection and, depending on the size of the map section, can take 15 to 20 minutes (for large sections).
…to be continued…
Source: pocketpcthoughts.com
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USB - Signaling
By admin | April 29, 2007
USB Signaling:
Pin numbers (looking as a socket):
| Pin assignments | ||
| Pin | Function | |
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1 | Vbus (4.75 - 5.25 V) |
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2 | D- |
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3 | D+ |
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4 | GND |
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Shell | Shield |
USB signals are transmitted on a twisted pair of data cables, labelled D+ and D−. These collectively use half-duplex differential signaling to combat the effects of electromagnetic noise on longer lines. D+ and D− usually operate together; they are not separate simplex connections. Transmitted signal levels are 0.0–0.3 volts for low and 2.8–3.6 volts for high.
Mini-USB Signaling:
USB Mini-A (left) and -B (right) plugs, showing pin numbers:
USB Mini-A and -B plugs (pictures):
| Mini-USB connector pinout | |
| Pin | Function |
| 1 | Vbus (4.75 - 5.25 V) |
| 2 | D- |
| 3 | D+ |
| 4 | ID |
| 5 | GND |
Most of the pins of a Mini-USB connector are the same as those in a standard USB connector, except pin 4. Pin 4 is called “ID” and, in the Mini-A connector, is connected to ground, but in the Mini-B is not connected. This causes a device supporting USB On-The-Go (with a Mini-AB socket) to initially act as host when connected to a USB Mini-A connector (the “A” end of a Mini-A–Mini-B cable). The Mini-A connector also has an additional piece of plastic inside to prevent insertion into a slave-only (B-only) device.
Source: http://en.wikipedia.org/wiki/Usb
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USB - Packet Format
By admin | April 29, 2007
USB packets have a format very similar to the packets used on the very early internet. It is nearly impossible to clearly understand USB connectivity without understanding the structure of the USB packet.
USB Packet Format:
| OFFSET | TYPE | SIZE | VALUE | |
| 0 | HeaderChksum | 1 | Checksum of the header by adding the header bytes, excluding the header checksum. | |
| 1 | HeaderSize | 1 | Size of the header, including strings if applicable. | |
| 2 | Signature | 2 | Signature: 0×1234 | |
| 4 | VenderID | 2 | USB Vendor ID | |
| 6 | ProductID | 2 | USB Vendor ID | |
| 8 | ProductVersion | 1 | Product version | |
| 9 | FirmwareVersion | 1 | Firmware version | |
| 10 | UsbAttributes | 1 |
USB attributes: Bit 0: If set to 1, the header includes all three strings: language, manufacture, and product strings; if set to 0, the header does not include any strings. Bit 2: If set to 1, the device can be self powered; if set to 0, it cannot be self powered. Bit 3: If set to 1, the device can be bus powered; if set to 0, it cannot be bus powered. Bits 1 and 4 … 7: Not used. |
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| 11 | MaxPower | 1 | Maximum power the device needs in units of 2 mA. | |
| 12 | Attribute | 1 |
Device attributes: Bit 0: If set to 1, the CPU speed runs at 24 MHz; if set to 0, the CPU speed runs at 12 MHz. Bit 3: If set to 1, the device’s EEPROM can support 400 MHz; if set to 0, it can not support 400 MHz. Bits 1, 2 and 4 … 7: Not used. |
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| 13 | WPageSize | 1 | Maximum I2C write page size | |
| 14 | DataType | 1 |
This value defines if the device is application EEPROM or device EEPROM. 0×01: Application EEPROM 0×02: Device EEPROM Other values are invalid. |
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| 15 | RpageSize | 1 | Maximum I2C read page size. If the value is zero, the whole PayLoadSize is read in one I2C read setup. | |
| 16 | PayLoadSize | 2 | Size of the application, if using EEPROM as an application EEPROM; otherwise the value is 0. | |
| 0xxx | Language string | 4 | Language string in standard USB string format if applicable. | |
| 0xxx | Manufacture string | … | Manufacture string in standard USB string format if applicable. | |
| 0xxx | Product string | … | Product string in standard USB string format if applicable. | |
| 0xxx | Application Code | … | Application code if applicable. |
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USB - Transfer Speeds
By admin | April 28, 2007
USB supports three data rates.
- A Low Speed rate of 1.5 Mbit/s (183 KiB/s) that is mostly used for Human Interface Devices (HID) such as keyboards, mice, and joysticks.
- A Full Speed rate of 12 Mbit/s (1.5 MiB/s). Full Speed was the fastest rate before the USB 2.0 specification and many devices fall back to Full Speed. Full Speed devices divide the USB bandwidth between them in a first-come first-served basis and it is not uncommon to run out of bandwidth with several isochronous devices. All USB Hubs support Full Speed.
- A Hi-Speed rate of 480 Mbit/s (57 MiB/s).
Though Hi-Speed devices are commonly referred to as “USB 2.0″, not all USB 2.0 devices are Hi-Speed. A USB device should specify the speed it will use by correct labeling on the box it came in or sometimes on the device itself. The USB-IF certifies devices and provides licenses to use special marketing logos for either “Basic-Speed” (low and full) or High-Speed after passing a compliancy test and paying a licensing fee. All devices are tested according to the latest spec, so recently-compliant Low Speed devices are also 2.0.
Hi-Speed devices should fall back to the slower data rate of Full Speed when plugged into a Full Speed hub. Hi-Speed hubs have a special function called the Transaction Translator that segregates Full Speed and Low Speed bus traffic from Hi-Speed traffic. The Transaction Translator in a Hi-Speed hub (or possibly each port depending on the electrical design) will function as a completely separate Full Speed bus to Full Speed and Low Speed devices attached to it. This segregation is for bandwidth only; bus rules about power and hub depth still apply.
A hub will have one or more Transaction Translators and there is no standard way to determine the number of transaction translators a hub may have. All low and full speed devices connected to one transaction translator will share the low/full speed bandwidth. This means that hubs can have dramatically different performance depending upon the number of transaction translators and the devices plugged into their ports. e.g. a hi-speed 7 port hub with only 1 transaction translator with 7 low/full speed devices plugged in, will act no differently than a USB 1.1 hub and all devices compete for the same low/full speed bandwidth. If the hub were to have a transaction translator for each of the seven ports, then each device would have all the full/low speed bandwidth available to it and would only compete for the hi-speed bandwidth, which is much greater.
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USB - Error Handling
By admin | April 28, 2007
Considerable error checking and error handling features have been built in to the USB to ensure that it is a reliable method of connecting peripherals to a PC. Data integrity should be comparable to that of an internal expansion bus.
Immunity from data corruption by noise and spikes has been provided by the use of differential logic drivers and shielded cabling. When errors do occur, cyclic redundancy checks (CRCs) performed separately on both the control and data fields of packets will enable 100 per cent recovery of both single and double bit errors. Unrecoverable errors can be detected with a high degree of confidence.
A self-recovery mechanism is built into the messaging protocol, with time-outs for lost and invalid packets. Some error recovery is built into the hardware. The host controller will retry a failed transaction three times before reporting an error to the client software. How a reported error is dealt with is the responsibility of the client software.
Interrupt and bulk data transfers conclude with a handshake packet to provide confirmation that the data was received, or request that it be re-sent if it was not. Delivery of this data is therefore guaranteed, even if the time taken to deliver it is not.
With isochronous data it is not possible to retry a failed transaction. Since only one ‘slot’ is allocated to the pipe during each frame, resending the data would delay transmission of the succeeding data samples, upsetting the time element of the data delivery. Consequently no handshake packet is sent and the data must be accepted ‘as is.’
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USB - Bus Protocol
By admin | April 27, 2007
Information transfers over the bus are called transactions. At any time the host controller may have a list of transactions that are waiting to be actioned. A transaction begins when the controller sends a packet describing the type and direction of the transaction, the 7-bit USB device address and the endpoint number. This packet is called the Token Packet.
The source of the data – either the controller or a device depending on the direction – then sends a Data Packet. In most cases the transaction is completed by the destination of the data sending a Handshake Packet which is either an ACK, indicating the data was accepted, a NAK, indicating that the data was not accepted, or a STALL, which signals that the endpoint is stalled.
Traffic on the USB is regulated using time. The unit of time is the frame. The length of each frame is governed by the bus clock, which runs at a rate of 1KHz, so there are 1,000 frames per second: one per millisecond. At the start of each frame a Start Of Frame (SOF) packet is sent over the bus, allowing isochronous devices to synchronise with the bus.
The concept of frames is central to how the bus shares out bus bandwidth among the various competing devices. The USB designers felt that it would not be possible to support several concurrent isochronous communication flows with fast sample rates using a system where each device must interrupt the host for each sample of data to be transferred. Consequently they designed the system so that isochronous devices are given guaranteed bandwidth by allocating them a proportion of the time in each frame.
At least 10 per cent of every frame is reserved for use by control transfers. This proportion can be increased by the system software if performance is found to be suffering through control packets being unduly delayed. The maximum continuous throughput over USB must therefore be less than 90 per cent of the signalling rate.
Part or all of the remaining time in each frame can be reserved by pipes serving isochronous devices. The actual portion allocated to each pipe is pre-negotiated when the pipe is set up. This ensures that a specific amount of data can be transferred every millisecond. Any bandwidth remaining is available for other types of transfer.
Isochronous devices must buffer data one frame’s worth at a time, and send each block over the bus as a single transaction. At the receiving end the data is unbuffered and restored to real time. For example, an audio device operating at a CD-quality 44.1KHz sampling rate would send nine frames with 44 samples per frame, followed by one frame with 45 samples. After buffering at the source and unbuffering at the destination there will be a delay of a couple of milliseconds in delivering the data, but the rate of delivery – which is what is important to preserve quality – will be preserved.
Interrupt transfers are also to an extent time critical. When a pipe is created for an interrupt endpoint, a desired bus access period of between 1 and 255ms (10 and 255ms in the case of low speed devices) is specified. The system software polls the interrupt endpoint at an interval which ensures that if an interrupt transaction is pending it is dealt with within the desired time-frame.
Source: http://www.tech-pro.net/intro_usb.html
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