CYBT-343026: XRES Pull-up resister value / GPIO when unused

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TaGo_2353976
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Hi,

Q1:

Could you tell me internal pull-up resistor value inside CYBT-343026 on XRES pint?

<Back Ground>

-XRES has internal pull-up according to the datasheet

-My customer would like to drive XRES pin from external CPU.

-They has a plan to put pull-down resistor on this pin in order to sense low during power-up sequence.

(External host has a time that this pin will be set "Un-Specified")

-In order to decide resistor value of pull-down, we need to know resistor value of internal pull-up inside CYBT-343026.

Q2:

If GPIO (0/3/4/6/7) , P4 and P24 pins are not used, can we leave these pins floating(OPEN)?

Thank you.

--TAK

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1 Solution

HI Tak,

Q1. Is there any possibility that the module will output radio during this time.

A1: Yes. If the reset pin is released after the VDD supply voltage level has been stabilized for 50ms(from datasheet), the module will work normally.

Q2.If the module may issue radio, I feel pull-down resistor is useful.

In order to decide resistor value, we need resistor value of internal pull-up resistor of XRES pin. Could you please tell ?

A2: If the external CPU has a strong drive capability, you can use a pull-down resistor. It’s better to ask customer what’s the value of their pull-up resistor.

The internal pull-up resistor of reset pin is 5.7kOhm.

Q3. In order to stop module, asserting XRES long time would be useful, or not?

A3: If customer want to keep the module not to work, just keep the reset pin low.

View solution in original post

6 Replies
AnjanaM_61
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5 comments on KBA First comment on KBA 5 questions asked

Hi TAK,

Q1) I don't think you have to connect a pull down resistor. You can connect / drive the pin directly from external CPU pin.

Q2) Yes, you can leave the pins floating .

Regards,

Anjana

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Hi Anjana,

Thanks for your answer.

>Q1) I don't think you have to connect a pull down resistor. You can connect / drive the pin directly from external CPU pin.

In the other words, Cypress does not recommend to connect pull-down resistor on this pin?

The customer "would like to " connect pull-down resistor to sense "Low" on this line during CPU is power-up.

Thank you.

--TAK

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Hi Tak,

Yes, we won't recommend pull down resistor.

Regards,
Anjana

Hello,

In the customer application, some customer will use their application without BT function including certified region in regulation point of view.

In this case, the customer would like to stop CYBT module by asserting XRES from external CPU but

there is a short timing that host CPU will set this pin "Open" during" power on sequence.

(Please see attached file(

I'm assuming that the FW that HFP AG will be started automatically will launch between VDD stable and XRES asserting Low.

<Question>

1.Is there any possibility that the module will output radio during this time.

2.If the module may issue radio , I feel pull-down resistor is useful.

   In order to decide resistor value, we need resistor value of pull-up resistor.

   Could you tell me it ?

3.In order to stop module, asserting XRES long time would be useful , or not?

Thank you.

--TAK

0 Likes

HI Tak,

Q1. Is there any possibility that the module will output radio during this time.

A1: Yes. If the reset pin is released after the VDD supply voltage level has been stabilized for 50ms(from datasheet), the module will work normally.

Q2.If the module may issue radio, I feel pull-down resistor is useful.

In order to decide resistor value, we need resistor value of internal pull-up resistor of XRES pin. Could you please tell ?

A2: If the external CPU has a strong drive capability, you can use a pull-down resistor. It’s better to ask customer what’s the value of their pull-up resistor.

The internal pull-up resistor of reset pin is 5.7kOhm.

Q3. In order to stop module, asserting XRES long time would be useful, or not?

A3: If customer want to keep the module not to work, just keep the reset pin low.