Easy tests?

RFM12 Wireless module discussion.

Easy tests?

Postby chrisw957 » Mon Apr 14, 2008 8:35 pm

I'm working on a rfm12b application with a 18f452. I think I have the bit banged input and output routines working, but it's hard to tell. If I remove and reconnect VCC to the unit and do a status register read, I think I see the power on reset bit (POR) set for one read. All the other bits are zero. Does that sound correct?

What registers can I write to do a quick test? I tried writing 0x8200 to disable the microcontroller CLK, but I still see the 1 mhz signal.
I tried writing 0xC0E0 to change the frequency of the microcontroller CLK, but it didn't change.

It's too bad that you can read the current settings of the registers.

thanks,
chris
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Re: Easy tests?

Postby seaton » Mon Apr 21, 2008 4:40 am

chrisw957 wrote:I'm working on a rfm12b application with a 18f452. I think I have the bit banged input and output routines working, but it's hard to tell. If I remove and reconnect VCC to the unit and do a status register read, I think I see the power on reset bit (POR) set for one read. All the other bits are zero. Does that sound correct?

What registers can I write to do a quick test? I tried writing 0x8200 to disable the microcontroller CLK, but I still see the 1 mhz signal.
I tried writing 0xC0E0 to change the frequency of the microcontroller CLK, but it didn't change.

It's too bad that you can read the current settings of the registers.

thanks,
chris



G'day Chris,

A couple of things I found when bit banging to the RFM12.

Make sure that the 16bit command is sent all at once and no interruption between bits.
You need to raise and lower CS in between each command.
Wait a few mS after power up before sending out the SPI commands.
Alos make sure that you timing is within the specs noted on the datasheet.

I used the CLK as a test to see whether my spi was getting through, I just changed from 1MHZ to 10MHZ and watched it on a scope or freq counter.

Also check that Reset is pulled high and you also have 10K pulling DATA high, even if it's not being used.

Do you have a scope you can monitor the SPI lines with?

Let me know how you go.

Stephen...
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