EV9900A Datasheet, PDF(7/27 Page) CML Microcircuits – Test Access for Important Signals

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EV9900A Datasheet, PDF (7/27 Pages) CML Microcircuits – Test Access for Important Signals

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Evaluation Kit for CMX990

EV9900A

3.3 Operation

The CMX990 is a complex RF and Baseband Modem IC. It is recommended that the user

familiarise themselves with the datasheet of this device prior to attempting to use the EV9900A.

To use the EV9900A the user will need a mechanism to send and receive data and commands

via the 8-bit parallel host ÂµController interface on the CMX990, which is brought out on connector

J13 on the EV9900A. The CMX990 datasheet gives details of the registers and commands. To

operate the CMX990, some typical command sequences are given below:

Data Rate

The default data rate with a 14.4MHz reference is 6000bps. Data rates can be configured using

the clock control register in the CMX990 (C-BUS address $29). The following example C code

shows a typical configuration for common data rates:

register_write(CLOCK_CONTROL, 0x45);

//9600 bps e.g. 25kHz channel

register_write(CLOCK_CONTROL, 0x85);

//4800 bps e.g. 12.5kHz channel

register_write(CLOCK_CONTROL, 0x46);

//8000 bps e.g. 12.5kHz channel

Receive Mode

The following example C code shows a typical configuration for reception.

register_write(POWER_UP_2, 0x08); //Reset

register_write(POWER_UP_2, 0x01); //Vbias on

register_write(POWER_UP_1, 0xEE); //Clock+BB+Vreg,+Rx:on & Opamps+Tx:off

register_write(POWER_UP_2, 0xF1); //DACs on

register_write(AUX_DAC_1_MSB,169); //AFC to mid rail (1.65V)

//Set up synths:

set_main_synth(0x8480,0x807530);

//750MHz, low side, Rx Freq=420.1MHz

//(assuming ref 14.4MHz & comp 12.5kHz)

set_aux_synth(0x8090,0x870C);

//180.4MHz (for 45.1MHz IF)

//(assuming ref 14.4MHz & comp100kHz)

register_write(CONTROL, 0xE9);

//AGC max gain & run, IQ offset fine,

//AFC Slow, PLL Narrow

register_write(MODE, 0xD2);

//IRQ enabled, scrambler enabled,

//INV bit enabled, Main ADC enabled, Rx mode

register_write(POWER_UP_2,0xF5); //Turn LNA on.

register_write(COMMAND, 0x60);

//Acquire DC offset & AFC

//DelayBy(90000);

//Wait for Offset to complete

Following the above routines the user may initiate reception of data using the modem task

commands in Command register ($01).

UM9900A/3

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