We are using 8 HMC807 Devices on the same SPI Bus. My question pertains to how we can use the lock detect function when all the devices are sharing the same LD_SDO Line.
Using the Evaluation Board and GUI, I have found that the Lock detect can be disabled via the following Registers:
xB - pfd_LD_opEn
x7 - lkd_enable
In my experience with the evaluation kit, after using the default register file for integer mode with 50mhz reference and observing the GUI to say "Locked".
When opening the "detailed GUI View", The LD_SDO line only goes low if I write a 0 to x7 - lkd_enable.
The LD_SDO line seems to be unaffected by toggling the xB - pfd_LD_opEn register bit.
Can someone advise on the proper way to disable the Lock detect function of the LD_SDO pin?
Additionally, Is there any other means to detect a lock on each individual HMC807 if they are all sharing the same SPI Bus(LD_SDO)?
I've attached the user guide which covers the HMC764, HMC765, HMC783 and HMC807; this is also available on the product page on analog.com. Please see page A-7,A-14, A-18, A-20 and A21.
REG 0x07 enables the internal LD function but the Flag is controlled in REG 0x0B. As you saw, you could reset this bit on the (7) devices that you are not interested in leaving only the (1) device that you are interested in set.
REG 08 is the GPIO pad driver and must be enabled in order to use the GPO (SDO) port but in the software this box is unchecked and LD functionality did not appear to be impacted.
REG 08 must also be enabled in order to use Lock Detect (LD). Alternatively to using Reg 0x07 you could disable this on the (7) devices that you are not interested in leaving only the (1) device that you are interested in. Using the GUI you'll notice that the device remains locked but the LD status indicates otherwise. Setting the bit and re-writing restores the status.
REG 0x0B outputs the LD flag to the SDO pin. Disabling does not appear to impact LD reporting.
REG 0x0F allows read back of the LD flag (value) where "1" equals locked. Disabling does not appear to impact LD reporting.