Just a few questions about the fsk version of the radio pair:
1: what length of wire do i need for an antenna?
2: does anybody have a better set of data on the pinout and the pin functions? the laipac datasheet is useless (and kind of slapstick-funny).
3: also, anybody have any good app notes for the thing? The few that are on the sparkfun site are kind of cryptic. What are the resistors on the input of the transmitter for? the diode, etc?
4: does the fsk pair do the fsk for you? In other words, does the transmitter encode low and high voltages into two diffrent frequencies (not radio frequencies, but slower on-off ones) and does the receiver decode those two frequencies back into levels? Or is it just somehow “fsk able” or something like that.
5: any tested schematics would be fantastic! I’ll keep hacking away at this and if i get it, i’ll be sure to post what i find out. These devices look really great and i feel like all they need is some more readily available documentation. I’ll do my part!
I’d use a 1/4 wave piece of wire. What is that math again…
c = 3e8m/s = 3e10 cm/s
3e10(cm/s) / 916e6(1/s) = 32.75cm give or take a cm.
The datasheet has some typos, but it’ll get you the pinout (more than I can get out of some suppliers). Using it conjunction with the app note:
Pin2) freq setup
Pin3) RF Enable (active high)
Pin5) VCC
Pin6) GND
Pin7) Ant
DCL is the input pin for high speed applications. DCH is for low speed.
Not sure why they have a reversed polarized cap with diode. Latchup prevention? The slower data pulses may effect the FSK format of the transmitter. The RCD circuit may setup and hold the data for longer… I’m rambling down a path a really don’t know.
The module will take care of all the frequency encoding for you. You may need to provide your own CRC or error dection via firmware.
Sorry - we haven’t had the chance to kick the tires on the 916 modules. I have played with the lower freq units with good results through a few projects long ago : http://www.sparkfun.com/tutorial/ADXL/glider-1.htm