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Craig Flanagan
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OTP VPP PIN

Hello I have been working on an application for some time now. It is based on the DA14585 MSK IOT design. I just had about 15 boards made

as a development/test platform for this product. I used the same pinout for the DA14585 shown in the DA14585_DB_IOT+VC_SCH. In this schematic,

pin 38 is just sent to a capacitor which is not placed. So after seeing this and after reading the datasheet for the DA14585 it seemed this pin was not

needed. So in my design I did not connect this pin (as you didn't). Now I read that I need to have the secondary bootloader programmed in order to

boot from the external flash memory I have installed  (as is installed on your MSK design as well). So in order to install the secondary bootloader

I suppose I need access to that pin 38 to set it to 6.8 volts for the OTP programming. I cant gain access to that pin now with the boards I had made.

Is this true? Is there a away around having to use this pin while still being able to boot from the external flash? How did you do this at the factory

(did you use a zif programmer or something like that) as I am surpised that you had the OTP programmed ahead of time on the chips before they

were soldered on the board (?) as there doesnt appear to be anything connected to your pin 38 on the schematic.

Please help. Thank you.  

 

 

 

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PM_Dialog
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Hi Craig Flanagan,

Hi Craig Flanagan,

Could you please clarify the GPIO of the DA14585 that you are talking about? Do you mean the VDD form the Figure 4 of UM-B-095 user manual?

Thanks, PM_Dialog

Craig Flanagan
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Yes, pin 38 labeled Vdd on

 

 

 

Yes, pin 38 labeled Vdd on Figure 4 of UM-B-095. Also if you reference the schematic that was released 

with the MSK kit, which I referred to, you will note that the capacitor which is connected to pin 38 is not populated. 

This indeed is the pin (pin38) which is not exposed/accessible on my new boards. In fact, another data point

I referenced in assuming exposing/routing out pin38 was not necessary is the statement in UM-B-095 which

says " VDD: INPUT. ○ This pin is used for testing purposes only."

I await your comment. Thank you. Craig

PM_Dialog
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Hi Craig Flanagan,

Hi Craig Flanagan,

Regarding the VDD pin, it’s an internal power supply rail that powers the digital part of the chip and the pin is used for monitoring that rail, so this pin should remain floating. In case you have a custom board with DA14485, please Table 3: Recommended Operating Conditions of the DA14585 datasheet. You should supply voltage on VBAT3V for OTP programming. The 6.6-6.8V supply voltage in Vpp pin is need only in the DA14580. This is mentioned in the Table 258: Recommended Operating Conditions of DA14580 datasheet.

Thanks, PM_Dialog

Craig Flanagan
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Many thanks. You folks are

Many thanks. You folks are always responsive and helpful. Craig

PM_Dialog
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Hi Craig Flanagan,

Hi Craig Flanagan,

Thanks for accepting my answer.

Regards, PM_Dialog