LMK03318: How to load the .tcs file into clock generator using Uboot I2C commands

Hi Sameeksh,

The .tcs file is a configuration file designed to be interpreted by the TICS Pro software. The device only needs to know the register settings associated with that configuration, which can be obtained by "File" --> "Export hex register values" in TICS Pro. Inside the hex register value file, each row refers to a specific register in the LMK03318 (e.g. R0) and has a hex value. The first two hex digits are the register hex address and the second two hex digits are the register value.

I assume that you want to program the device once on the production line and then have it manage itself afterwards. Then you will need to program the register information into the device's EEPROM, so it will start up with that configuration every time. I will explain the steps used for manual EEPROM programming.

• I am not familiar with U-boot but it is capable of carrying out I2C transactions (here is a tutorial I found on the internet: https://www.gibbard.me/uboot_i2c/). You should check if you can locate the device and issue read commands to it. If the read commands are successful, then the U-boot I2C interface should be compatible with the LMK03318 and you can proceed.
• The first step is to load the device registers with the values from the configuration. For every register in the hex register file, issue a corresponding write command. When you are done the device registers should be loaded with the correct settings for your configuration. These changes will be lost if you power cycle the device, so we are not done yet.
• Next, follow the "Write SRAM" process in section 10.5.4 of the datasheet. SRAM is a temporary holding place for register settings before programming them into EEPROM. Be sure to program the correct SRAM page that corresponds to the EEPROM page used in your design.
• Lastly, follow the "Write EEPROM" process in section 10.5.5. of the datasheet.  After this is done, power cycle the device and verify if it is behaving as expected and if the registers are the same as you programmed.

Let us know if you have more questions about the procedure, I may not be able to help much with U-boot itself.

Best,

Evan Su

Sameeksh,

The only difference between using 1.8 V, 2.5 V, or 3.3 V on the output supplies is the amount of current that would be drawn. Any of the output formats can be used with any of these supply pin voltages. 

See this excerpt from the datasheet:

Note that the LVCMOS outputs are always 1.8 V - the Status pins can be used for 3.3 V LVCMOS outputs.

Otherwise, any of the output format types can be used with any of the allowable supply voltages.

Thanks,

Kadeem

Hi Sameeksh,

To be extra clear, if you are wondering how to pick between output formats in TICS Pro (AC-LVPECL, AC-LVDS, HCSL, etc.), that decision should be made based on the specific requirements of each of your endpoints (ADCs, switch, processor, USB); their datasheets should say what kind of input clock they expect.

From an electrical signal perspective, the differential formats (LVPECL, LVDS, HCSL, CML) will specify a certain common mode voltage and a certain voltage swing. This swing will vary between formats but is independent of the supply voltage of the output driver, the receiver, or the endpoint. So if your FPGA is operating at 1.8 V for example, that does not tell me what kind of input clock it expects. The single-ended CMOS format is special because it swings rail-to-rail, so the supply voltage of the output driver needs to match the supply voltage of the receiver.

The configuration I provided you yesterday has everything set to AC-LVPECL but I do not know if all of your receivers expect AC-LVPECL clocks. If they do not, make the appropriate changes within the configuration. You may also need to review the schematic of your design to verify that the termination schemes are correct for each format. Let us know if you have specific questions.

Best,

Evan Su 

Hi Sameeksh,

In the programming process all operations can be carried out with a sequence of individual register writes, you should not need to write multiple registers as part of one I2C transaction. I think the "block" read/write the datasheet discusses is perfectly capable of addressing individual registers. The name may come from the fact that you are allowed to write multiple bytes to one starting address (which I would not recommend to start out with because it could be confusing).

I again have no experience with U-boot, but if you try using it to read individual registers in the device and the results are correct, then the I2C transactions should be formatted fine and you can proceed.

Best,

Evan Su

Hi Sameeksh, 
No problem I understand.

Once you have powered up, to pick page 1 of EEPROM, follow the steps listed below under the programming section of the LMK03318 DS: 

R145[3:0] should be set to 1'b to select page1. 

GPIO pins are checked on power up only to choose which EEPROM/ROM config to load. Once the device is on, you can program it as outlined above. 

Regards, 

Vicente 

Once you program EEPROM page 1, say you always want to load this config upon a power cycle refer to this table below: 

HW_SW_CTRL = 0 ; GPIO[3]= LO ; GPIO[2] = MID

Regards, 

Vicente