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SWIFI (Smart WIFI) integrates a Lantronix WiPort device server, high input voltage switching power supply, large 2Mbyte FIFO, and hardware flow control to achieve low loss real-time telemetry and message communications in a mobile robot environment with a less than ideal radio link.

radio status


  • 00-20-4a-b3-2e-cd ( w/WEP64 : IW purchased ~9-1-09
  • 00-20-4a-9f-56-9f ( : IW
  • 00-20-4a-b3-2e-f0 ( w/WEP64 : IW purchased ~9-1-09
  • 00-20-4a-9f-f1-3e ( w/WEP64 : IW purchased ~9-1-09
  • 00-20-4a-9f-99-86 ( : IW 7-2-09 : installed in SWIFI#2 when over-voltage. status unknown. seem flakey


  • 00-20-4A-9F-2B-F6 ( w/WEP64 : MIT w
    • Shutting off randomly when connected to ankle 8 for a few minutes (9/26/11)
  • 00-20-4a-96-46-53 ( w/WEP64 : MIT w
  • 00-20-4A-9F-3c-F6 (SW6 : w/WEP64 : MIT w
  • 00-20-4a-96-46-5a ( : MIT : location unknown

to order radios:

physical interface to robot


  • The hardware can be powered over the FUP port (WIP4a.PFUP1) or via the 3 pin header (WIP4a.PO3)
  • The unit accepts 15-30 volts and requires ~ 2watts

MC Comm (MIT Dataport Protocol)

This is the 5 position header (PFUP1) on the WIP4a. It connects to the motor controller FUP.

  • straight 1.25mm cable into 5 pin connector (See WIP4a.PFUP1 cable below)
  • connect to normal (RED) 5 header on FUP1.pcb
  • connect 9 pin 1.00mm cable to MOTOR CONTROLLER PORT pf UPD 200-218 (SC/MC)

SC Comm (MPD Message Protocol)

This is the 6 position header (PX1) on the WIP4a. It connects to the state controller FUP.

  • Uses special 5 to 6 position cable (See WIP4a.PX1 cable below)
  • connect to normal (RED) 5 header on FUP1.pcb
  • connect 9 pin 1.00mm cable to STATE CONTROLLER PORT of UPD 200-218 (SC/MC)


  • The Wiport becomes too hot to touch in normal operation. If placed in an enclosure, for long term reliability, it probably requires ventilation, and/or a heat sink.

diagnostics for AUTORESET

  • The SWIFI (on S2) now has an auto reset feature where the RESET signal on the WIPORT radio is assert for 250mS. This is necessary as sometime the WIPORT isn't able to re-establish a connection. The auto reset activates after 45 seconds of "idle". As long as the SWIFI has power, MIT comm data can continue to accumulate in the 2Meg SRAM and will be sent when possible.
  • The idle timeout is reset with the following events:
  1. A TCP connection is established (implies that either CP2 or CP3 go high). CP2 and CP3 control the green and yellow lights.
  2. The SWIFI sends data to the WIPORT (which means the robot is actively sending data to the SWIFI). This isn't a perfect as there is a 4k buffer to be filled before the SWIFI is unable to send data to the WIPORT.
  3. The "reset idle" ESC sequence is received on port 10001 (the MIT Comm port). Wifi_fast.py can send this every 5 secs, but decided to disable this and rely on #1 and #2.
  • When there is a connection:
  1. Red light pulses at 1sec.
  2. The red light also lights when data is send to the SWIFI from the PC.
  3. The blue light pulses when the MPD channel is sending data from the robot to the PC.
  4. The blue light is lit when the WIPORT is blocking data from the SWIFI.
  • When there is no TCP connection:
  1. The red light will flash at 2 hz.
  2. The blue light flash at 10 hz with a duty cycle equal the percentage 'fullness' of the 2 Meg SRAM.
  • When the WIPORT is reset (250mS)
    • The red light will flash at 20 hz.
    • The blue light will flash at 3hz. It will continue to flash at 3hz until the radio is booted.
  • As the WIPORT boots, the edge yellow lights will do their normal dance.

diagnostics (WIP4a - old firmware)

power up

  1. the red led lights to indicate power
  2. the yellow leds on the ENDs (DM1, DM7) will flash and bounce back and forth as the devices negotiates a connection with the access point
  3. the orange and blue LEDs (DM4 and DM5) light briefly during boot
  4. when booting is complete the right side LEDs (red and yellow) will be lit.

when active

  1. established TCP connections on port 10001 and 10002 cause DM2 and DM3 to be lit
  2. each MPD message will case the flash of the ORANGE LED (DM4), the robot's answer will cause the BLUE LED (DM5) to flash briefly
  3. when the dataport is active, and the WIPORT is unable to accept data - the BLUE led will light. (A blue flash without a preceding red flash suggest this case). Some flashing of the BLUE LED is normal as radio packets are lost and retransmitted. Continuous illumination of the BLUE suggest that the TCP connection is broken (is GREEN led lit?). Short term this is not a problem as the WIP4 can buffer minutes of data.

LED details

  • DM1 (orange) WiPort diagnostics LED - flashes when booting
  • DM2 (orange) indicates a TCP connection on port 10002 (MPD PORT - SC)
  • DM3 (green) indicates a TCP connection on port 10001 (DATAPORT - MC)
  • DM4 (red) short flash when data received from port 10002
    • longer flash when a command ESC sequence is detected.
  • DM5 (blue) short flash when data transmitted on port 10002
    • long flash when the CLEAR SRAM FIFO command is received.
    • continuously lit when Wiport when communication on 10001 is blocking.
  • DM6 (red led) indicates 3.3V supply
  • DM7 (orange) indicates radio power / active communication (flashes with)

cable construction

5pin for PFUP1

  • both ends use 5 position, 1.25mm housings (digikey WM1723-ND)
  • build with 5 wires, appx 6" in length
  • this is a straight cable, pin 1 to pin 1, etc.

6pin for PX1

  • both ends use 1.25mm housing. One end is a 5 position (WM1723-ND), the other a 6 position (WM1724-ND)
  • built with 5 wires, appx 6" in length
Pin to pin connections:
Pin# (PX1) 6pos Pin# (FUP on SC) 5pos Signal names
1 5 GND - GND
3 2 SDO - FUP.TX
4 3 SDI - FUP.TX
5 4 SS - FUP.IO
6 1 V+ - V+

Special config of the Wiport

After configuration of the Wiport via serial port, connect with a web browser and complete the configuration:

Options 0:

Network mode: 0=Wired Only, 1=Wireless Only, 2=Bridging(One Host) (1) ?

IP Address : (192) .(168) .(192) .(214)
Set Gateway IP Address (N) ?
Netmask: Number of Bits for Host Part (0=default) (0)
Set DNS Server IP addr  (N) ?
Change telnet config password (N) ?

Then Option 4:

Topology: 0=Infrastructure, 1=Ad-Hoc (1) ? 0
Security suite: 0=none, 1=WEP, 2=WPA, 3=WPA2/802.11i (0) ? 1
Authentication: 0=open/none, 1=shared (0) ?
Encryption: 1=WEP64, 2=WEP128 (1) ? 1                  <===== WEP64, others take too long to connect
Display current key (N) ?
Change Key (N) ? Y
Key type 0=hex, 1=passphrase (0) ? 1
It is strongly recommended to use a passphrase of 20 chars or more!

TX Key index (1) ?
TX Data rate: 0=fixed, 1=auto fallback (1) ?
TX Data rate: 0=1, 1=2, 2=5.5, 3=11, 4=18, 5=24, 6=36, 7=54 Mbps (7) ?
Enable power management (N) ?
Enable Soft AP Roaming (N) ?

Then Option 9 (save and exit)


  • TCP keepalive : 10 sec
  • CPU performance : high

Chan 1 and Chan 2

  • (serial settings) 921600 baud, CTS/RTS hardware
  • (connection) Telnet com port ctrl : disabled

Configurable Pins

  • 1 : Diagnostics LED HIGH
  • 2 : Modem Ctrl Chan 2 OUT HIGH
  • 3 : Modem Ctrl Chan 1 OUT HIGH