Tip / Sign in to post questions, reply, level up, and achieve exciting badges. Know more

AIROC™ Bluetooth

yuta_4555331
Level 1
10 sign-ins 5 replies posted 5 sign-ins
Level 1

I would like to check about the CTS/RTS Pin condition of the HCI UART port of CYBT-343026-01.

The following library states that the CTS pin must be at a high level at reset in order to enter HCI mode.
>https://community.cypress.com/t5/Resource-Library/Run-CYW20706-in-HCI-Mode/ta-p/246397
>(2) Pull the CTS to high during power on reset or hardware reset.)

Is there any specification for RTS?
Also, what is the HW pin configuration of the CTS and RTS pins during reset? (e.g. Input Pullup).

 

The next question is about the CTS/RTS pin condition when using UART in RAW mode. Are the conditions same to HCI mode or different?
>https://community.cypress.com/t5/Knowledge-Base-Articles/How-to-Use-HCI-Raw-Data-Mode-in-CYW20706-KB...

 

The last question, can I use the HCI UART without flow control (without CTS/RTS) if I adjust the pin conditions of CTS/RTS to the initial conditions of the above question?

BR

0 Likes
1 Solution
AnjanaM_61
Moderator
Moderator First comment on KBA 5 questions asked First question asked
Moderator

Hello @yuta_4555331 

I checked internally and below is the suggestion from our team. 

For CYW20706 based module,  If flow control (for HCI UART ) is not desired, pull BT_UART_CTS_N pin to ground (via 10Kohm pull down resistor) and leave BT_UART_RTS_N floating. 

Regards,

Anjana 

View solution in original post

0 Likes
12 Replies
AnjanaM_61
Moderator
Moderator First comment on KBA 5 questions asked First question asked
Moderator

Hello @yuta_4555331 

Flow control pins are needed for HCI UART communication. 

Can you please clarify whether your end product will be in HCI only mode or using embedded mode in which you will use HCI RAW data ? 

https://community.cypress.com/t5/Resource-Library/Run-CYW20706-in-HCI-Mode/ta-p/246397 - This blog should be referred only in case if you are using the module in HCI only mode. In that case , (2) Pull the CTS to high during power on reset or hardware reset will ensure the HCI UART will stay in a state to accept the incoming HCI command from host.  

In case of HCI UART RAW mode , You need not have to control HCI UART CTS / RTS pin explicitly. Please only follow the software configurations needed as in the blog here:  https://community.cypress.com/t5/Knowledge-Base-Articles/How-to-Use-HCI-Raw-Data-Mode-in-CYW20706-KB... 

 

Regards,

Anjana

0 Likes
yuta_4555331
Level 1
10 sign-ins 5 replies posted 5 sign-ins
Level 1

Thanks for the reply.
I plan to use UART RAW mode for our end product.

I understand that to operate in UART RAW mode, HCI UART CTS / RTS pin control at reset is not needed and software setting is required.

I have a new question here.
Even if I use the software setting to make it work in UART RAW mode, if the CTS pin is H level at the Reset state, does it become HCI mode?

>Flow control pins are needed for HCI UART communication.
I think it can be used if the risk of missing data is acceptable, but is there any other reason why it is necessary?

0 Likes
yuta_4555331
Level 1
10 sign-ins 5 replies posted 5 sign-ins
Level 1

Hi, @AnjanaM_61 

Could you reply for my additional questions?

Best regards

0 Likes
AnjanaM_61
Moderator
Moderator First comment on KBA 5 questions asked First question asked
Moderator

Hello @yuta_4555331 

I checked internally and below is the suggestion from our team. 

For CYW20706 based module,  If flow control (for HCI UART ) is not desired, pull BT_UART_CTS_N pin to ground (via 10Kohm pull down resistor) and leave BT_UART_RTS_N floating. 

Regards,

Anjana 

0 Likes
yuta_4555331
Level 1
10 sign-ins 5 replies posted 5 sign-ins
Level 1

Hi, @AnjanaM_61 

>pull BT_UART_CTS_N pin to ground (via 10Kohm pull down resistor)

Is it acceptable to connect directly to GND without a resistor?

 

0 Likes
AnjanaM_61
Moderator
Moderator First comment on KBA 5 questions asked First question asked
Moderator

Hello @yuta_4555331 

As per our HW team, recommended way is to pull down via a 10Kohm pull down resistor.

Regards,

Anjana

0 Likes
yuta_4555331
Level 1
10 sign-ins 5 replies posted 5 sign-ins
Level 1

Hi, @AnjanaM_61 

I understood that recommendation is pulldown via 10kohm but is there any functional difference from direct GND connection?
(For example, the reset state changes depending on the value of the Pulldown resistor.)

It would be great if you could check with the HW team.

0 Likes
yuta_4555331
Level 1
10 sign-ins 5 replies posted 5 sign-ins
Level 1

Hi @AnjanaM_61 

I'm in a bit of a hurry, so if you could let me know as soon as possible, I'd appreciate it.

0 Likes
AnjanaM_61
Moderator
Moderator First comment on KBA 5 questions asked First question asked
Moderator

Hi @yuta_4555331 

Sorry I missed your last query. I will check this internally and update you asap.

Regards,

Anjana 

0 Likes
AnjanaM_61
Moderator
Moderator First comment on KBA 5 questions asked First question asked
Moderator

Hello @yuta_4555331 

I checked with HW team, their recommendation is to use 10K pulldown resistor.

CTS is an output signal on 20706. During power up, this pin is high and will draw excess current if tie to GND directly.

Regards,

Anjana

0 Likes
yuta_4555331
Level 1
10 sign-ins 5 replies posted 5 sign-ins
Level 1

Hi @AnjanaM_61 ,

The CTS pin should be an input signal.

There is no functional difference between pull-down and direct GND connection, right?

0 Likes
AnjanaM_61
Moderator
Moderator First comment on KBA 5 questions asked First question asked
Moderator

Hello @yuta_4555331 

There should not be any functional difference for CYW20706. However our internal HW team have evaluated only with a pull down resistor. 

In case of other BT chips like CYW20719, CYW20819 etc this will make a functional difference & hence not recommended to ground HCI UART CTS pin at all. 

Regards,

Anjana

0 Likes