Question about Linx RF module's (HP3) datasheet

[Megahertz]

I have read datasheet of the above modules (TX & RX) but I would like some help understanding two key points in the datasheet (attached).

Firstly, if I want to select the channel serially, I take the clock pin HIGH, data pin LOW, both I believe can be connected directly to any free pins on my PIC (set as outputs), and then use debug statement to transmit binary value of between 1 to 100 to the data pin (for example "DEBUG 01100100 " for 100 & " DEBUG 0011" for 3, and immidiately after doing this take and keep clock and data high all the time.
Secondly, should I send 8 bits every time? like for 3, should I always send "DEBUG 00000011"?
Thirdly, will sending data this way will make LSB go first?
Fourthly , is this a correct process to set the channel I want to use serially?

And LASTLY, at page 10 of the datasheets, under the table where serial channel chart is on the right, I am not sure what colum 3 means under the heading "RX LO" & also why on both Tx & Rx datasheets it is only mentioned TX Frequency & not RX centre frequency in the RX datasheet?

[Megahertz]

Anyone ? please help.....

[Dave]

Megahertz , I would send the string " DEBUG $64" instead of "DEBUG 01100100 " What you are sending is a string of ascii 0's and 1's. I beleive the module is looking for a single HEX character equivalent value... This way you will always be sending 8 bits... And YES, the serial data presented by DEBUG is LSB first, just as in normal RS-232, assuming that is the format the module is looking for data to be presented...

Dave Purola,
N8NTA

[Bruce]

RX LO is just the local oscillator frequency fed into the mixer on a superhet receiver. When you change the TX frequency, it also has to change the receive frequency.

Check http://en.wikipedia.org/wiki/Superheterodyne_receiver and scroll down to the Overview section for a brief explanation, or lookup superhet receiver design online for the nitty-gritty details.

Also - the HP3 series serial communications will not work with DEBUG or any other asynchronous (means no clock) since it is synchronous (means it requires clock & data) serial.

Check out http://linxtechnologies.com/Documents/AN-00155.pdf for a code example of serial communications with an HP3 series.

[Megahertz]

RX LO is just the local oscillator frequency fed into the mixer on a superhet receiver. When you change the TX frequency, it also has to change the receive frequency.
As a novice I would still like to ask, TX frequency channel is changed by sending a serial command to the TX module, I got that loud and clear, how is RX channel selected, is it by sending excatly the same command to the RX module? & rest is taken care by the module itself?
I am very confused :confused: because on TX datasheet it says clearly that what to send and what will be the TX frequency, BUT on RX datasheet it doesn't say what to send and what will be the RX centre frequency, instead it mentions excatly the same thing as in the TX datasheet, which I think is only for changing TX channel. It may be a small thing to undertstand but I am still not getting it clearly.



Also - the HP3 series serial communications will not work with DEBUG or any other asynchronous (means no clock) since it is synchronous (means it requires clock & data) serial.

Check out http://linxtechnologies.com/Documents/AN-00155.pdf for a code example of serial communications with an HP3 series.

I checked the link for the example code with serial communication but it is in assembly language which unfortunately I can't understand :(
Is there any other link somewhere showing same or similar code in PBP, PLEASE point me to it?

[Bruce]

The receiver accepts the same commands as the transmitter when selecting the operating frequency. I suspect they goofed when putting the receiver data sheet together. Obviously, since it's a receiver, you're not configuring a transmit frequency...;o)

I've never used these so I don't have any PBP code examples. Sorry.

Since it requires synchronous serial, I would bet you can use PBPs shiftout command.