Notes

Power Consumption (5V power supply)

Current CPU     Ethernet         TS-9441
  0.35A 200Mhz  ON+connected     no
  0.36A 200Mhz  ON+connected     yes
  0.29A 200Mhz  ON+disconnected  yes
  0.25A 200Mhz  OFF              yes
  0.20A 166Mhz  OFF              yes  
  0.16A 41.5Mhz OFF              yes
  0.20A 41.5Mhz ON+disconnected  yes
  0.27A 41.5Mhz ON+connected     yes
  0.10A 14.7Mhz OFF              yes

Conclusions
  TS-7400 requires 450mW MINIMUM, 1750mW at FULL
      50mW  (0.01A) TS-9441
      350mW (0.07A) Ethernet connection
      200mW (0.04A) Ethernet PHY
      250mW (0.05A) 166->200Mhz
      200mW (0.04A) 41.5->166Mhz
      300mW (0.06A) 14.7->41.5Mhz
  which implies the following power above minimum:
    - 850mW for Ethernet to be working usefully (41.5Mhz minimum CPU speed)
    - 750mW for 14.7->200Mhz

Shell Functions

dio_dir_get n
  get the current direction (0=input,1=output) of DIO #n (n in 0..15)

dio_dir_set n dir
  set the direction of DIO #n to the specified direction (0=input,1=output)

dio_data_get n
  get the current value (0=Low,1=High) of DIO #n

dio_data_set n val
  set the current value (0=Low,1=High) of DIO #n
  (specified pin should be set to be an output already)

usb_init
  call this function to turn the USB ports on and initialize them

usb_off
  call this function to turn off the USB ports

usb_numports
  prints the number of USB ports on the board.  this may be greater then
  the actual number of physical ports.  the first port is port 0.

usb_port_devexists port
  prints '1' if something is plugged into the specified port, or '0' otherwise.

eth_off
  turns off the ethernet port and phy

eth_on
  turns on the ethernet port and phy

led0 state
  sets the state of the green LED (0=OFF,1=ON)

led1 state
  sets the state of the red LED (0=OFF,1=ON)

cpu_speed_max
  set the CPU and bus speed to their maximum (normal) values, 
  e.g. 200Mhz/100Mhz.

cpu_speed_166
  set the CPU speed to 166Mhz and the bus speed to 66Mhz.

cpu_speed_42
  set the CPU speed and bus speed to 41.5Mhz.  This is the slowest speed 
  that Ethernet will work at.

cpu_speed_min
  set the CPU and bus speed to their minimum values (14.7456Mhz)

temp_read
  returns the current Celsius temperature reading from the TMP124 chip.