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03-22-2017 08:09 AM
I have a some questions related to configuration of the CP2114.
- For the I2S bus lines, I am connecting the audio output to an Si7413 transmitter IC; and looking at the application schematics between the two, the Si4713 shows resistor values of 2K for DCLK and DFS and 600 Ohms for DIN. However, on the application schematic for the CP2114, it shows resistor values of 33 Ohms for all three pins. Since both these ICs will be on the same PCB in close proximity to each other, do I need to use these series resistors at all? If so, which values are most appropriate?
- For unused GPIOs on the CP2114, do I need to use a pullup resistor or can I leave these pins floating (Specifically speaking of GPIO.0 through GPIO.4). If pull-ups are required, what value do you recommend (4.7k?)
- For the configuration pins, how do I define the User-programmed configurations? I understand that configuration data can be stored in the device's one-time programmable ROM. Does this mean that the ROM holds these 11 different User-programmed configurations?
- For the User-programmed configurations, can the config pins be switched on the fly to change the configuration settings, or are these pins only read on startup/reboot?
- Can the CP2114 be configured through Simplicity Studio? From looking at AN721, it seems like the Xpress Configurator utility is what I need to use. However, when I search for the CP2114 in the Xpress Configurator Project Setup dialog box, it does not show up in the list (The closest results I see are various options for the CP2110 and CP2112. I did run a software update to make sure I'm not missing anything. Are there any additional utilities/add-ins I need to have for this to work?
Solved! Go to Solution.
03-23-2017 03:58 PM
Some answers from the top of my head:
2) Pull-ups aren't required, usually. By default, the GPIO's have weak pull-ups enabled (to the tune of ~100k Ohms). If the weak pullups are disabled (a user option), you should provide your own.
5) Sadly, CP2114 isn't supported in Xpress Configurator (yet!). You'll need to use the CP21xxCustomizationUtility found in the AN721SW.zip: http://www.silabs.com/documents/public/software/AN721SW.zip
This zip is also found in Studio if you go to the AN721 dialog that allows you to open the folder at the pdf location...
03-23-2017 11:29 PM
Here is my comments on your questions:
1. Recommend adding series resistors to mitigate noise on these digital audio signals. AN383 also provides more design guidelines for Si47xx devices, including these resistors.
2. It is fine to leave unused GPIO pins float, normally there is a weak pull-up on these pins if it is not disabled.
3. There are up to 32 different audio configurations supported by the CP2114 device. The CP2114 ships with three different audio configurations, user can program it with their own configurations if necessary. For more details, please refer to section 3.6 One-Time Programmable ROM (page 22) in the CP2114 Datasheet v1.2
4. Configuration can be controlled by the setting in the ROM or by these Config Select pins. The programmed configuration determined by the boot index will be loaded after reset, also see the datasheet for more info about this.
5. As Brian mentioned above, user currently need to use the AN721SW to program the CP2114 configuration.
03-25-2017 10:33 PM
Thank you for your detailed responses. The things you shared did clear up most of my questions. I do have some additional questions concerning your response to my question 1.
I did look through AN383 as you advised, and I saw on page 10, a table describing the propose for the resistors on SCLK, DFS, and DCLK as being a "current limiting resistor" in the value range of 25-2k. Mitigating noise makes sense, but is it necessary if both the chips on both ends of the line are right adjacent to each other on the PCB (with the longest trace being about 0.3 inches long), rather than separated via a cable or other long length of line?
As for the other responses. I just received a dev board fro the CP2114 yesterday and will begin testing. I'll Post back again once I have had a chance to try out your suggestions.
03-27-2017 01:04 AM
Based on page 6 of AN383, series resistor on DCLK/DFS/DIN pins are required when using digital audio input. Place these register as close to the host controller as possible, and need to confirm that timing requirements are met with the selected resistor value.
Therefore in my opinion, add these registers on your PCB, but you can adjust the register value if necessary, referring to the Table 8 and Figure 8 for digital audio interface timing parameters in Si4713 datasheet v1.1.
03-27-2017 07:28 AM