User's Manual

XBee®/XBee‐PRO®ZBRFModules
©2009DigiInternational,Inc. 132
XBee-PRO modules must also set a couple of IO lines to enable output power compensation. This
is shown below. Once the IO lines are initialized (after powerup), the XBee will enable the power
amplifier and LNA as needed.
On Powerup:
/* GPIO 2 should be set low for at least 10 milliseconds when coming up from power cycle. */
GPIO_DIRSETL = GPIO(2);// Set GPIO 2 as an output
GPIO_CLRL = GPIO(2);// Drive GPIO 2 low
/* After at least 10ms, GPIO 2 should be set high to power the output power compensation
circuitry.
At the same time GPIO 1 should be configured as an output and set low to enable the output
power compensation circuitry. */
GPIO_DIRSETL = GPIO(1) | GPIO(2);// Set GPIO 1,2 as outputs
GPIO_CLRL = GPIO(1);// Drive GPIO 1 low
GPIO_SETL = GPIO(2);// Drive GPIO 2 high
Improving Low Power Current Consumption
To improve low power current consumption, the XBee should set a couple of unused IO lines as
output low. This can be done during application initialization as shown below.
XBee (non-PRO) Initialization:
/* GPIO 1 and 2 are not used in the XBee (non-PRO) and should be set as outputs and driven low
to reduce current draw. */
GPIO_DIRSETL = GPIO(1) | GPIO(2);// Set GPIO 1,2 as outputs
GPIO_CLRL = GPIO(1) | GPIO(2);// Set GPIO 1,2 low
XBee-PRO modules should disable the power compensation circuitry when sleeping to reduce
current draw. This is shown below.
When sleeping (end devices):
/* The power compensation shutdown line on XBee-PRO modules (GPIO 1) should be set high
when entering sleep to reduce current consumption. */
GPIO_SETL = GPIO(1);
When waking from sleep (end devices):
/* The power compensation shutdown line on XBee-PRO (GPIO 1) should be set low to enable the
power compensation circuitry and LNA. */
GPIO_CLRL = GPIO(1);