Sending 6 bits from PIC18 to another IC via SPI

[pratiken]

Hi guys,

I'm close, but am having trouble sending 6-bits to an IC that expects only 6 bits from my PIC18F2550.

DATASHEETS:
PIC: https://ww1.microchip.com/downloads/en/devicedoc/39632c.pdf

Hittite IC: https://www.hittite.com/content/documents/data_sheet/hmc624alp4.pdf

This is what the oscilloscope shows:



I think the last two bits are screwing up the attenuator. I can send all 1's and all 0's and that will make it go LOW or HIGH but if I try to send something like 0b010000 to get an attenuation half way then it won't work.

Is there a way to limit the clock cycles to 6 and not 8 so that only 6 bits get send out?

Here's my basic code from MikroC:

#include <stdio.h>

unsigned int i;
unsigned char myByte = 0b111111;
void init(void){
     ADCON0 = 0;
     ADCON1 = 0x0f;
     TRISB = 0;
     TRISC = 0;
     //TRISB.B1 = 0; // SCK
     //TRISC.B7 = 0; // SDO
     SPI1_Init_Advanced(_SPI_MASTER_OSC_DIV4, _SPI_DATA_SAMPLE_MIDDLE, _SPI_CLK_IDLE_LOW, _SPI_LOW_2_HIGH);
}
void main() {
     init();

     while(1){
     Delay_ms(1);
              LATB.B2 = 1;

              SPI1_Write(myByte);
              LATB.B2 = 0;
              Delay_ms(100);

     }

}