I'm working with the Si5345-EB REV 2.1, which I'm able to configure using the ClockBuilder Pro software. Once the design is transferred to the EVB, everything works as expected.
Next step for me is to achieve the same programming using a c bare-metal program installed in an external microcontroller. To this end, I first generate the configuration file with the ClockBuilder to be added to the C program, and the spi bus of the microcontroller (4-Wire at 1.8 V, not 3.3 V!) is connected to the spi interface of the evaluation board (J36, with the jumpers removed).
I have read and understood how the spi programming sequence is (an926-reading-writing-registers-spi-i2c.pdf), and, indeed, I'm able to write and read the whole set of registers provided in the configuration file (I write them all and then read them again to check if they were correctly written; apparently, they are). However, when I run this program, that writes the preamble, configuration registers and post-amble, the clocks never start.
There is a single exception: if I program the clock with the clockbuilder, then connect my spi and finally reset the clock, then the clock starts correctly after running my code. Basically, if the chipselect of the spi bus is kept high while reseting, then my software is able to start the clock properly. I assume that this is due to some configuration that the ClockBuilder is doing and my software isn't, and remains in memory even after reseting the clock if the chipselect is kept high. Any suggestion about which could be this configuration? Am I missing anything else?
Some additional information: as commented, I'm using the default file provided by ClockBuilder Pro. I've also tried adding the additional registers that clockBuilder is programming but not adding in the configuration file (and that can be obtained via the clockBuilder EVB GUI). The jumper JP4 is kept in the evaluation board (I2C_SEL = 0) and IO_VDD_SEL = 0 via 0x0943 (1.8 V). There is no reference, so the clock should start in free run mode.
ok, as per the answer in this other thread, a few jumpers need to be shortened to get the VDDO regulators working. Now I need to know which.