RCcoms
From GT RoboJackets
The wireless communication for the Robojackets 2007 robocup competition robot will facillitate communication between the host computer and the robot players. Transmission will be full duplex using both a transmitter and a reciever. with the host computer broadcasting directives to all robots at once or in sequence in real-time. Each robot will send status information back to the host, but not in real-time.
Contents |
The Wall
06/20/06 I looked up the price of the dev kit for the Linx modules. You get everything you need but it cost $299.99 on digikey. Here is a link to it Dev kit.
11/23/06 - Finally got the wireless modules to work. It looks like they can't be ran at exactly 56Kbps. Made changes to run at 55.9Kbps. This has also affected system clock speed.
Here is a link the module we are going to use. It was also used by the team from CMU. The HP series readios provide a low latency path and are implemented as a seperate reciever and transmitter. An external co-processor will handle all transfers with the modules.
To Do
- Robot Wireless system
Design ProtocolChoose wirelss co-processorSchematic for wireless comm board- Write code for co-processor
Order parts and breadboardGet wireless comm board made out- Will be integrated into main board- Test protocol and packet drop rate
- Host computer wireless system
- Design board for host comm with robots. Should be straight fwd same as robot but this time as a stand-alone so sperate pwr and it'll need to go to a DB-9.
Wired Communication System
- Direct Wired Serial RS-232 Interface
- Possible choices of cards:
- Equinox Multi-Port Adaptors
- Features:
- 2-16 full-duplex lines
- Offloads serial processing from CPU
- Equinox Multi-Port Adaptors
Comment: Should we implement the wired/wireless systems at the same time?
Comment: Yes, also can we just stream data to it and assemble packets on the board? What we want is something that can make the wireless connection as transparent as possible.--Phillip
Articles
- Article on Selecting a Wireless Module
- Real-Time issues and 802.11 (Bad Link, Please Fix)
- Article on RF
- TI Article on Wireless Design
Linx Applications Notes
- RF 101
- Modulation Techniques
- Antannae Design
- Protocol Design
- Using the Serial Line to Select Channels
Specifications
| Device | Serial to Wireless transmitter and reciever |
|---|---|
| Interface | RS-232: rate selectable up to 19.2K, 8 data bits |
| Wireless Interface | 900MHz Serial Packet modem |
| Modulation | FM/FSK |
| Data Rate | 55.9 kbps |
| Range | 30M |
| Output power | 15dB |
| Frequency | 900Mz |
| Rx Sensitivity | -100db |
| Protocol | Proprietary, See protocol page |
| Power | 3.3V, <0.014A |
| Antenna | Board Mounted Coaxial |
| Latency | Low |
| Co-Processor | Same as main processor |
Schematics
Starting from scratch. That idea was a rough guess at the best.
