I'm looking to implement an ECO crystal (24.576MHz to support proper I2S transmission on 48khz sample rate). In "AN218241 PSoC6MCU Hardware Design Considerations", page 8. the diagram shows that the ECO crystal shall be connected to P12_6 and P12_7 AND the pins grounded. I have only seen
similar practice in GHz circuits, not on MHz level, so I suspect the AN diagram is wrong. Can someone from Cypress please confirm the correct hardware connection and update the application note document for other people?
I believe you are correct. The two pins should connect the GND via caps. The doc AN218241 needs to be revised.
I will raise a internal ticket for fixing this issue.
Please have a look at the CY8CKIT 062 WIFI-BT schematics as reference in the meantime, there an ECO is connected to the chip.
Thanks for the answers. Interestingly, the 062 WIFI-BT does have external load capacitors. Are they necessary as well? In PSoC creator there seems to be the capacitance setting (same as BLE ECO); we'd prefer to use the internal capacitors to avoid external components.
No, it is not necessary to add the load capacitors in the BLE ECO pins, because we have add it inside of the chip. You can configure it in the .cydwr--> clocks to change the load cap value.
For all the crystal(no power), it is necessary to add the load cap. Unless it has added it inside of the chip.
If there are any misunderstandings of the topic, welcome to talk about it.
Still unclear :-). I do know that BLE ECO does not need external capacitors, they are implemented in the chip. My questions is about the ECO on pins P12_6 and P12_7. WangS_81 clearly states:
"The internal hardware blocks of ECO and BLE ECO are different. For ECO connection, the external caps are indispensable."
This indicates that I need the caps and I have already provided the pads in my design just to be safe. However, then what does the load caps option in PSoC creator do (see picture below)? As LinglingG_46 says:
"For all the crystal(no power), it is necessary to add the load cap. Unless it has added it inside of the chip."
So does this option adds the seleted capacitance inside the chip? These two answers seem to be in conflict.
Moreover, if I add the external caps, what should this capacitance set to?
The below is my understanding about this:
For P12_6 P12_7 ECO, customer should fill in the crystal parameter depending on the crystal device datasheet.
The ECO parameter function is described in the below figure:
More about the information, you can refer the PSoC6 Architecture TRM in below linker: (Section ECO)
If anyone is familiar with the BLE ECO, welcome to share the experience.
Hope it can be a bit helpful for you.