MICRF505DEV1 Micrel Inc, MICRF505DEV1 Datasheet - Page 18

• Manufacturer Part Number: MICRF505DEV1
• Description: KIT DEV RADIOWIRE 850-950MHZ
• Manufacturer: Micrel Inc
• Series: RadioWire®r
• Type: Transceiver, ISMr

Specifications of MICRF505DEV1

• Frequency: 850MHz ~ 950MHz
• For Use With/related Products: MICRF505
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 576-1606

MICRFXXX: User Manual for Development System, FW v.4
Automatic hopping between frequencies is implemented. For MICRF505/MICRF600: To
meet the FCC part 15.247 regulations. The units will jump approx. 10 times/second:
For the MICRF506, -610 and -620: less than 25 frequencies are used, but the frequency table
holds 25 entries. That is, several “frequency indexes” points to the same frequency.
There is an internal timer in both Master and Slave. The timer is a 3-byte (24-bit) timer; the 3
bytes are called Timer_Upper, Timer_High and Timer_Low. A Timer_Low overflow will
generate an interrupt every 0.37msec approx (with a 11.0592MHz xtal connected to the micro
controller). In the interrupt service routine (ISR) the Timer_High and Timer_Upper registers
are updated.
Timer_High will overflow every 256*0.37msec = 94,8msec. This overflow is used to indicate
“time-to-change-frequency” (a flag is set in ISR, the flag is tested in the main program).
Whenever Timer_High overflows, Timer_Upper is incremented.
When the main program detects time-to-change-frequency, it uses Timer_Upper as an index
in a frequency look-up table, where the frequencies are randomly stored. That is: The next
index will not give the next frequency, but a random frequency.
The internal timer of the master is never changed. The internal timer of the slave is updated
whenever a frame from master is received.
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