Sitara am4377 : pinmux , adc0 and adc1

Hello,

Thanks for reaching out on this issue. I am going to get some information from our ADC experts and will get back to you with more information before the end of the week. 

BR,

Hi

Any leads ? 

Any inputs? This issue hold us off from starting prototype production

Hello Inno,

Apologies for the delayed response, see details below:

Can I ignore the power domain warning on pin AC25 and connect this pin to 3.3V without damaging the AM437x?

You should never completely ignore power domain warnings as applying incorrect voltages to a device pin will cause damage, refer to the device-specific Data Sheet for more details.

If not, can I still connect VDDSHV2 to 3.3V (and still get power domain warning on pin AC25), but this time connect pin AC25 to 1.8V via level shifter?

If not, how can I resolve this issue?

A level shifter is a good solution for a trigger signal between different voltage domains.

See this information on TI's Voltage Level Translators https://www.ti.com/logic-circuit/voltage-level-translation/overview.html

Is it Ok to define pin AC25 as “ext_hw_trigger” in SysConfig for the internal ADC0 only (in order to avoid the resource conflict indication), but actually use it for ADC0 and ADC1?

If not, how can I resolve this issue?

Each ADC has a designated set of trigger input signal options (SW & HW). The ext_hw_trigger has two ball options (D24/AC25) according to datasheet.

It seems that the D24 is not enabled to support the ext_hw_trigger signal in the SysConfig Tool. This may have been done on purpose, if not, a bug will be filed to have the AM437x device SysConfig Tool data corrected to support both options.

Regardless of tool, you should use D24 for the ADC1 ext_hw_trigger signal and AC25 for the ADC0 ext_hw_trigger signal.

Thanks for the answer , but it lacks conclusive solutions and information that will allow us to close this issue :

"It seems that the D24 is not enabled to support the ext_hw_trigger signal in the SysConfig Tool. This may have been done on purpose, if not, a bug will be filed to have the AM437x device SysConfig Tool data corrected to support both options"

This answer is not too conclusive : is this a bug with the tool or not ? I need to start prototype production and this is one of the key issues that holds us from going forwards. What do you suggest we do ? can we copy the idk am437x design ?

"Regardless of tool, you should use D24 for the ADC1 ext_hw_trigger signal and AC25 for the ADC0 ext_hw_trigger signal"

In dual sampling mode - which should be used ? AC25 ? Note that with the idk am437x ac25 is used (and connected to  ePWM3_SyncOut), and can operate both ADCs (on the code we have made). is this a valid behavior or a glich / bug I should not rely on ?

How do we finalize a design without a concrete answers ?

is this a bug with the tool or not ? I need to start prototype production and this is one of the key issues that holds us from going forwards. What do you suggest we do ? can we copy the idk am437x design?

The AM437x IDK HW design has been verified and should be used as reference point. I will dig into why the SysConfig tool does not support configuring D24 as ext_hw_trigger for ADC1.

In dual sampling mode - which should be used ? AC25 ? Note that with the idk am437x ac25 is used (and connected to  ePWM3_SyncOut), and can operate both ADCs (on the code we have made). is this a valid behavior or a glich / bug I should not rely on ?

As mentioned in previous answer, if solution has been used in the IDK then it has been verified, in this case, rather then using using 2 true external ext_hw_tigger signals provided to two seperate balls each devoted to ADC0 and ADC1 respectively, the trigger signal is provided to AC25 (ADC0 ext_hw_trigger, and eHRPWM3_SYNCO (AB18) and ADC1 is configured to use the internal sw trigger rather than the true external trigger being used by ADC0. This is valid behaviour.