Zipper Tx_EN use?

I’m trying to use the Zipper to send 12bit QPSK data from a microcontroller to the Myriad RF 1.

I send the data to the Tx[0:11] pins and the appropriate bit to the IQ_SEL pin. The problem I’m having is with the Tx_EN pin. Whatever I do, the data is only sent when the pin is not connected; this can’t be normal behaviour, can it?

On top of this, the signal I see on the spectrum analyser is quite garbled and I kind of thought it would have something to do with this.

Any ideas?

You must have TX_EN set to high and also the soft TX enable in the lms6002d. I believe it is register 5.

The hard X_EN and Soft_EN are logical ANDED together. Also you have to make sure your LPF/TX PLL are configured properly.

One problem could be that the TX PLL is not locked properly. To do this you must adjust the VCO cap (register 19) to lock the PLL.

There are a lot of registers to setup in the lms6002d.

Thanks for the reply.

After messing about with it today I realised it worked when tied to the +V rail so there must have been a problem with my microcontroller not giving the right output.

I’ve been setting all the registers with LMS-Suite so that wasn’t the problem, but thank you.