RF12 module need to convert some C to Basic

[davewanna]

Hi,

I have a few RFM12 modules that I have posted on here about before. I have started to delve into the coding side of things, but am somewhat lost. The datasheets for these modules have examples coded in C. But I currently have absolutely no knowledge of C. Can someone who knows picbasic, and C please point me in the right direction?

The module is 'programmable' for a LOT of options. I am interested in getting just one to work, then I should be able to find my way from there. It has an osc output that can be used to supply the pic. I currently have that working, but at the default 1Mhz. This is the setting I have been attempting to change, as it should be easy to spot.

The register is in the datasheet at: http://www.hoperf.com/pdf/RF12.pdf Page 22, item 14.

according to what I can see, changing that register to 1100000011110111 should change the osc output to 10Mhz, and the low voltage detector to 4.5V

The C example of how to do this, from what I can see uses a command called write.

Code example is at: http://www.hoperf.com/pdf/RF12_code.pdf Page 20.
The piece I'm particularly interested in is when it calls a subroutine called "WriteCMD()" and has the following:

void WriteCMD( uint CMD )
{
    uchar n=16;
    SCK=0;
    nSEL=0;
    while(n--)
    {
        if(CMD&0x8000)
          Write1();
        else
          Write0();
        CMD=CMD<<1;
    }
    SCK=0;
    nSEL=1;
}

Can this be done in picbasic via shiftout, or serout?


I am using a 16f877a


Thanks in advance as always....

[davewanna]

As I said I don't know any C.. But looking at the code more, I have just noticed that Write0 and Write1 seem to also be subroutines...

void Write0( void )
{
  SDI=0;
  SCK=0;
  NOP();
  NOP();
  NOP();
  NOP();
  NOP();
  NOP();
  NOP();
  NOP();
  NOP();
  NOP();
  NOP();
  NOP();
  NOP();
  NOP();
  NOP();
  NOP();
  SCK=1;
  NOP();
}

My revised question is:
What is NOP() ????

[mackrackit]

Table 15-2 of the 16F877A data sheet says a NOP = No Operation

I can not help with the "C".

[davewanna]

Ok, so it seems that a NOP() is a nothing... which I assume is a timing thing. I can't really see how it turns a piece of HEX data into a string of ones and zero's and outputs them..

Surely there is a simpler way of doing this in picbasic? Should it respond to a serout command?

I thought I had researched all I could before I posted.... I know no-one is replying yet.. but I think asking the questions is helping my brain somehow.

Still open for assistance!

[davewanna]

Thanks mackrackit... I just found that out as you posted...

Pity no-one has example code of these modules in picbasic.. would make my learning procedure easier...

[Ioannis]

Have you just tried to send this binary string with shiftout?

I think there is not much needed to make it work. Just send the string. Serout will not work here.

Ioannis

[davewanna]

Ioannis,


I have not used shiftout before... I have just tried..

SCK             var portb.6
SDO             var portb.7
shiftout SDO, SCK, 1, [%1100000011110111]

This did not change the osc... still 1Mhz. Is my syntax ok?

[skimask]

void WriteCMD( uint CMD ) <-uint CMD takes in an unsigned integer
{
    uchar n=16; <-unsigned character (byte) set to 16
    SCK=0; <- SCK to logic low
    nSEL=0; <- nSEL to logic low
    while(n--) <- while/wend loop, n gets decremented by 1 each time thru
    {
        if(CMD&0x8000) <- if high bit of CMD is set then
          Write1(); <-call the Write1() sub
        else
          Write0(); <-otherwise do this one
        CMD=CMD<<1; <-shift it left by one
    }
    SCK=0; <- SCK to logic low
    nSEL=1; <- nSEL to logic high
}

I might be totally wrong...not that familiar with C...but to me this means:

WriteCMD:
n = 16 : SCK = 0 : nSEL = 0
for nn = 16 to 0 step -1
if cmd.15 = 1 then
gosub write1
else
gosub write0
endif
cmd = cmd << 1 : sck = 0 : nSel = 1 : return

Write0:
SDI = 0 : SCK = 0 : pauseus 16 : SCK = 1 : return

Write1:
SDI = 1 : SCK = 0 : pauseus 16 : SCK = 1 : return

And your issue might've been that you didn't turn the nSEL line on/off before writing out to the port...unless you didn't include that part in the posts.

[Ioannis]

I really wonder if the skimask's example will work because is the same shiftout command.

I have also ordered a couple of the modules (the high power ones) but will be delay and cannot test them right now.

Ioannis

[skimask]

I really wonder if the skimask's example will work because is the same shiftout command.
Ioannis

It is the same...
I think the only difference is toggling the SEL line.

[davewanna]

Skimask,

Thankyou for doing that... From the little bit of C that I have learnt in the last 24 hours, that looks good.

I did try nSEL last night with a couple of code attempts, but I did not try it consistantly.

I did also try to use the SSP last night for a short period. No luck yet, but I didn't expect it to be easy, I haven't used the SSP yet.

I am off to work now, but will try again later today.


Thanks for the assistance.

[Ioannis]

It could be a timing issue. No time to check now. If anyone could?

Ioannis