Specifications

PWM
Three pins support hardware PWM, refer to GPIO_8, GPIO_9, and GPIO_10 (These pins are also
referred to as TMR0, TMR1, and TMR2 in the MC1322x data sheets).
Serial rates
1200-65535 bps as well as 115.2Kbps (115.2Kbps is specified using a “baudrate” of 1).
Network IDs
The MC13224 hardware does not function properly with all network IDs. An MC13224 node set to a
network ID that fits the pattern 0xn2nn or 0xnAnn will not be able to receive radio transmissions,
though it can still send them. This is an issue with the underlying Freescale radio.
For example:
Network ID 0xFADE does not work. Network ID 0xFBDE does work.
Platform-Specific SNAPpy Functionality
Noise Floor (NV Parameter 33):
You can adjust NV Parameter 33 on MC13224 nodes to tune the node’s sensitivity to background
noise to prevent improper triggering of the Carrier Sense and Collision Detect features (if they have
been enabled). The parameter is specified in negative dBm, with a range from 0 to 127. Setting the
value too high (closer to 127) will cause the unit to interpret the background “noise floor” as real
communications, and can prevent the node from broadcasting if Carrier Sense and/or Collision Detect
are active. Setting it too low will render the Carrier Sense and Collision Detect features useless.
The default value is 57. Changes take effect only after rebooting.
Clock Regulator (NV Parameter 65):
MC13224 implementations offer sleep modes that use the external crystal (if available), and other
sleep modes that do not rely on an external crystal. NV Parameter 65 allows you to regulate the
internal clock (the one that does not use a crystal) to adjust for differences in your hardware and
environment. For most accurate timing, you may need to adjust this value depending on the ambient
temperature and the operating voltage of your node.
The range for the value is 0-0xFFFF, and the default value is 0x1F8F. The change takes effect only
after the radio restarts, which can be caused by several things. For the greatest predictability, it is
recommended that you reboot the node after setting this parameter.
This parameter has no effect on odd-numbered sleep modes.
Page 178 of 202 SNAP Reference Manual Document Number 600-0007K