Orthotic Knee

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Taken from : http://scripts.mit.edu/~biomechatronics/wiki/index.php?title=Kens_Orthotic_Knee_-_Spring08

Ken's Orthotic Knee

Knee Computer

  • Two (May9th) BLMD6 / BLMDFT6 were modified to run the orthotic brace
  • BLMDFT6 is populated with ACS712-30 current sensors M2, M3 - signal names IMOT.U, IMOT.W2. These appear at ADC.DMA CH1 and CH0 / ADC.MUX AN0 and AN6
  • BLMDFT6 was modified (M1/M4 removed) to allow to connection of two POTs, this signals replace the current sensors M1 and M4 with signal names IMOT.W and IMOT.U2. They appear at ADC.DMA CH3 and CH2 / ADC.MUX AN2 and AN1. Six wires were added. Red wire attaches to AVCC5. The white with green tip to AGND, and the white (signal input) to ACS712 (not installed) output pin. The signal input passes though a voltage divider (10k / (10k+20k)) to a opamp follower. Thus input load impedance is 6.7k.
  • The BLMD6 software was modified to remove the May9th style debug interface, and the SPI communications. The main loop now runs at ~1KHz (based on 3 ticks of timer3 which is synced to the MPWM module). The main loop calls the function statemachine() in statemachine.c.

Wireless Interface

  • Lantronix Wiport is connected to both the ankle and knee conputers
  • Wiport is configured to operate at 230,400 on channel 1, and 460800 on channel 2. Channel 1 operates as TCP port 10001 (raw mode), and channel 2 TCP port 10002 (TELNET MODE)
  • The various Wiports may be used on the ankles. Typically they'll connect to networks with SIDs of "biomech417", or "media lab 802.11". They may also operate in ad-hoc mode.
  • IPs for "biomech417" ankles (ALHPA2 / ALPHA3) is and

WIP2C Config

  • CP0 : GPIO
  • CP1 : Diag high
  • CP2 : SC1 Low
  • CP3 : MCout1 High
  • CP4 : SC2 Low
  • CP5 : MCout2 High

Wiport Cable

  • This cable connects the Wiport to both the AKCPU2B on the ankle and to the BLMD6 on the Knee
  • Power for Wiport comes from the AKCPU2B
  • Wiport connector is 8 position, 28 AWG (green) similar to A30992 (26 AWG)
  • Ankle.AKCPU2B connector is 7 pos, 1.25mm (PURPLE), and connects to 'dataport'
  • Knee.BLMD6 connector is 8+ position 1.25 (PURPLE STRIP), and connects to 'SPI port' and is RIGHT ALIGNED

Wiport Connector

  1. Blk : GND
  2. Red : VBAT (10-28V)
  3. Brn : Tx0 (TTL level Wiport output)
  4. Org : Rx0
  5. Blu : Tx1
  6. Gry : Rx1

Ankle.AKCPU2B Connector

  1. Red : VBAT
  2. NC
  3. Blk : GND
  4. Brn : Rx2 - dsPIC 2nd Async input (Wiport Tx0)
  5. Org : Tx2 - dsPIC 2nd Async output (Wiport Rx0)
  6. NC
  7. NC

Knee.BLMD6C Connectors

  1. NC : (one or more pins)
  2. Blk : GND
  3. NC
  4. NC
  5. NC
  6. NC
  7. Blu : Rx1 - dsPIC first UART input (Wiport Tx1)
  8. Wht / Gry : Tx1 dsPIC first UART1 output (Wiport Rx1) (ALIGN TO RIGHT EDGE)