HMC834 problem communicating with SPI


I'm having problem communicating with HMC834 on a custome PCB that I built for prototype. I'm sure I got all the connections correct, I followed eval board for referance. I'm using raspberry pi to test the circuit. I'm using modified "spidev_test" app to test spidev_test.c, but i've replace "tx" array to read "Reg 00".

uint8_t tx[] = {(1<<7),0,0,0}; // (1<<7) so first bit is set and HMC is in read mode.

but instead of getting 0xA7975 (which is the chip id) I'm getting 0x00. I've set chip in HMC mode by togelling SEN after rpi bootes up. I've used same code on other devices like RF module, and gyroscope to read status register to confirm validity of code.

My question:

1) I only see 450us as min wait for setting SPI mode no max time. Could it be that rpi is taking too long to boot and set SEN and HMC is in unknown state.

2) I see that SPI timing diagram in data sheet is little different than what i've usually seen, could that be why im facing this problem. Is HMC chip SPI interface different that standard SPI? So bit banging should fix the issue? How do you connect to SPI of HMC chips?

3) It's possible that i burned the chip while i manually reflow soldered it. Is there some way i can check if the chip is damaged, perhaps by checking resistance between pins and comparing to standard values or something similar?


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