LMX2492EVM: ISP SPI programming

Hi Bert,

Yes the LMX programming interface is compatible with SPI
DATA <--> MISO
CLK <--> SCK
LE <--> RESET
MUXout <--> MOSI


The programmer we use contains the MSP430F5529.

Regards,

Brian Wang

Hello Brian,

Thanks for confirming the SPI programming signals for the LMX series of TI.

I made a small investigation of SPI /ISP interfacing and Pin assignemts of the SPI connector of some LMX units of TI and Atmel,

If you are intersted I will send the PDF .

By the way I found a  minor mix up in the pins nomenclature.

DATA <--> MOSI (Master Out Slave In)

CLK <--> SCK

LE <--> RESET

MUXout <--> MISO (Master In Slave Out)

New SPI Level Question;

All LMX EVM boards do have a resistor attenuation network of 10k/12k and 12k, dividing voltage level to 40/50 %, why is this done.

Can I connect 5 V TTL SPI Level  signals to LMX2492 and LMX2595 EVM (VCC=3,3V) .

Kind regards

Bert

Dear Noel / Brian,

 We are trying to control the LMX2492EVM with an External trigger signal.

All is working fine in the Auto Ramp mode, but in the external Ramp mode the SPI interface is pulling the Input Trigger signal to higher bias voltage, Disabling external triggering function.

 So we programmed the LMX for Trig1 external trigger input (A) and ramping TrigA (via SPI) Auto-Ramp OFF and finally after we removed the SPI uWire from the EVM board the Ramp started to work.

 Both USB to SPI interfaces USB2ANY and Reference-Pro  do pull up at least Pin 1 (Trig1) (of 10-PIN SPI connector-interface)  by  approx. 1 Volt, (10K and 12 k in place).

We now are triggering the LMX with a pulse biased to -1 volt DC and Peak 2 V from DC. If now the SPI uWire is installed we have Pulse signal of 2 Vpp from DC, all is working fine now, External Ramp-Sweep triggering and still having all TICs=Pro factions

This information would be usefull in the application note SNAU160E.

Kind Regrds

Bert