Latest revision as of 20:14, 18 September 2007

• Motor
• AnkleSoftwareSpec2007Sep

State Machine (Master) Controller

• 25.38V max supply voltage (6 cell LiPoly, estimated Rs of 100mohm), 16.5V min input when motor operational, electronics should remain operational to 15V
• IIC EEPROM for controller parameters (RECMD: 24LCxx)

Off board interfaces

Switch Input

• externally mounted switch (logic levels) input for mode control

External ASYNC Serial Communication and ISP

• Ability to support a variety of attached serial devices (with external converter): eg wired RS-232, Bluetooth, USB, 802.11, and ISP.
• 1Mbaud (max) RS-232 level ASYNC serial (Tx, Rx, RTS, CTS) :
• Power for external devices: 5V and Vbat (with 0.20amp self resettable fuse)
• ISP signals (PGC, PGD, MCLR) for external ISP
• signals: Vbat, Vcc5, GND, Tx, Rx, RTS, CTS, PGC, PGD, MCLR -- try to keep same pinout as on original
• also include standard debug header, if room permits

Power / Data to Motor Controller

• logic level ASYNC 2-wire serial between SM and motor controller CPUs
• logic level output to motor controller fault pin to disable PWM (short motor leads?)
• logic level input for motor controller alert status
• (Vbat) battery power from motor controller
•  ??? sense path to battery for voltage monitoring; sense differentially using 2 inputs to ensure accurate reading
•  ??? board to board stacking connector (more reliable that wires)

Strain, SEA, Motor Temp, Supply current

• 5 analog inputs to CPU, analog bandwidth DC to 500 Hz, 12-bit ADC (sequential)
• 2 x 10k(or more) thermo resistor (requires opamp follower) for IMU temperatures : AGND and signal
• 2 x strain gauge bridges (340 or 1k ohm) to high gain (RECMD) INA326 : AGND, SG+, SG-, bridge reference
• 1 x analog input for SEA hall sensor board (discuss type of input) HMC1501: 3.3V, AGND, signal, signal2?
  • SG bridge reference voltage through 0.1% resistance (1k to reduce bridge current) ideally from AVCC3.3 (ADC reference) or from AVCC5

Pager Motor

• 3 pin header
• ability to turn on/off pager motor (3.3V)

On board sensors

Ambient Temperature

• Thermo resistor (>=10k) with opamp follower placed very close to IMU ICs (or epoxied to each of them)

Supply Voltage Monitor

• (better than) 1% accurate measurement of battery voltage (prevent over-voltage during regeneration)

IMU

• 3 DOF accelerometer, 2 DOF rate gyros (in PCB plane)
• 3-axis (SPI) accelerometer RECMD LIS3LV02DQ
  • this sensor will be (nearly) always powered and used to wake the processor

• XY axis (analog) rate gyro RECMD IDG300
  • Note: XY is in circuit board plane

AVCC5 monitor

• If SG bridge is powered from AVCC5 then we need to measure AVCC5/2, and SG bridge offsets depend on AVCC5

LEDs

• 2 LEDs mounted so as to be externally visible

Low Power Support

• Design for overall low power
• Target for sleep power of 5mW (0.12WHr/day - from VBAT), processor is sleeping.
• RS232 output interface disable (Rx still active - eg SN75C3223 - although baud rate may change to due primary clock sleep)
• Control of supply to internal sensors : ambient temperature, IMUs
• Control of supply to external sensors : SG, SEA, motor temperature

Sensor Power

• EC30 MR-ENC 15.5mA @ 5V : 77.5mW
• EC30 HALL SEN 10.6mA @ 5V : 53mW

• SG : 73mW(340ohm/5V), 10mW (1k/3.3V), 2.7mW(1k/1.6V)

• IDG300 9.5mA @ 3.3V : 31.mW
• ADXRS300 6-8mA @ 5V : 35mW
• ADIS16100 7-9mA @ 5V : 40mW

• ADIS16006 1.5-1.9mA @ 3-5V : 5 mW
  • has 1mA power down mode. 20mS wake up
  • sensitivity : 0.03%/C, 0.1lsb (1:20000) +-3% cross axis
• LIS3LV02DQ 0.6-0.8 @ 2.2-3.3V : < 2.6mW
  • programmable sleep mode with <10uA supply current
  • has programmable acceleration alarms to wake CPU
  • sensitivity : 0.025%/C, 0.2mg/C (1:10000 / C), +-3.5% cross axis

• ankle angle pot : 0.1-1mW

• Power supply (LT3470) efficiency 70%>5mA, 60%@1mA, 35%@0.1mA, (0.6mW from Vbat when LT3470 enabled and unloaded)