User manual

Code Mercenaries

5.7 Power supply

USB does allow a device to be "Bus Powered".

This means the device does get its power off the

USB port. To avoid overloading on the USB ports

devices need to advertise their power requirements.

There are two power classes for devices: Low

power and high power. Low power devices may

draw up to 100mA off the USB, high power

devices up to 500mA.

Likewise there are high power and low power

ports. Usually high power ports are those on the

motherboard and on hubs with external power

supply or hubs in a monitor. Low power ports are

typically on hubs that get their power off the USB,

like hubs in keyboards.

If the system decides that there is not sufficient

power to supply a high power decive that device

does not get enabled.

IO-Warrior can operate either as a high power or

low power device. Pulling the P0.0 pin on IOW40

or the Power pin on IOW24 high or low at reset

sets the desired power rating.

This allows to configure IO-Warrior optimally for

supporting external circuits.

5.8 Suspend

All devices on the USB port need to support the

suspended state. When the host computer stops to

periodically access the USB, like when it goes to

sleep, all devices need to enter the suspended state

and drop their power draw to less than 500A for

low power devices or less than 2.5mA for high

power devices.

When entering suspended state IO-Warrior pulls

all pins high. Care must be taken in designing

external circuits so that they will draw no more

than the allowed suspend power rating while all

pins of IO-Warrior are high.

5.9 Remote Wakeup

IO-Warrior chips support the remote wakeup

feature. They are able to wake the host computer

from sleep state if the host operating system has

enabled this feature.

Remote wakeup is initiated by IO-Warrior if any

pin is pulled low while the chip is in suspended

state.

V 1.1.0, December 2nd 2013, for chip revision V1.0.3.0 and up