Energy scan

Application

The energy scan enables the 16 IEEE 802.15.4 channels to be monitored in order to detect other radio systems. The energy in a frequency band is determined and displayed. Each channel is measured for approx. 5 seconds before moving to the next channel. Care must be taken that a channel does not communicate during these 5 seconds. It therefore makes sense to repeat the scanning of the channels a couple of times in order to obtain a more accurate statement as to whether or not a channel is occupied. The energy level is displayed through 0...0xF; "0" means no energy, "0xF" or 16dec stands for high energy level.

Set bit 1 in CB1 to TRUE. The KM6551-0000 confirms this in the status with bit 1, which is then also set to TRUE. The scan is finished when bit 1 of SB1 goes to FALSE. The result is then available in the input data byte 0 to 7. Each channel then corresponds to a nibble, i.e. half of a byte.

Example

The result is to be interpreted as follows. Channels 2 and 5 are to be avoided at all costs, but channels 3 and 16 look very good. No energy was measured here. Please note that these are instantaneous values. You can exclude channels with a high energy from further searches for free channels, but channels with no or only moderate energy may lead under certain circumstances to entirely different results.

Example: activation of the energy scan

Set bit 1 to TRUE in order to start data exchange.

CB1

The terminal sets bit 1 of the status byte SB1 to TRUE as long as the scan is active.

SB1

The terminal resets bit 1 of the status byte SB1 to FALSE once the scan is finished. You can now evaluate the input data bytes 0...7 (bytes 8-9 have no meaning and should not be evaluated).

The scan takes approx. 80 seconds.

SB1