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HaSh_1328096
Level 1
Level 1
10 questions asked 5 questions asked First reply posted

Hi,

FM3 CY9B110T Series.

It seems like UART max baud rate is 8MHz, Why isn't it 14.4 MHz?

In the document 'FM3 Peripheral Manual Communication Macro Part (TRM)',

following formula is shown.

V = φ/ b - 1

  V : Reload value  

  b : Baud rate

     φ: Bus clock frequency or external clock frequency

CY9B110T Series APB2 Bus clock is max 72MHz and  V is min 4.

Even considering the allowable baud rate range for reception,

Maximum baud rate is..

b = φ/( V + 1 ) = 72 Mhz  / ( 4+1 )  = 14.4Mhz  ( baud rate max )

However, in the data sheet it is 8 MHz.

(※Document History 03/09/2017 Added the Baud rate spec in “12.4.10 CSIO/UART Timing”)

■CY9B110T Series, 32-bit Arm® Cortex®-M3 based Microcontroller Datasheet

 https://www.cypress.com/file/252801/download

■32-bit Microcontroller FM3 Peripheral Manual Communication Macro Part

 https://www.cypress.com/file/211101/download

Why is this?

Is it because the specification of MFT needs 8 clocks

for setting the interrupt flag by checking the reception idle status?

Is there any other reason?

Best regards.

Shimoda

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1 Solution
Takashi_M
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1000 replies posted 500 solutions authored 750 replies posted

Apologize for the late response...

Your baud rate calculation for UART is correct.

b = φ/( V + 1 ) = 72 Mhz  / ( 4+1 )  = 14.4Mhz  ( baud rate max )

The all baud rates described in page 102, 104, 106, and 108 of CY9B110T Series datasheet are for CSIO. And, the maximum baud rate for CSIO is 8MHz.

https://www.cypress.com/file/252801/download

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Takashi_M
Moderator
Moderator
Moderator
1000 replies posted 500 solutions authored 750 replies posted

Apologize for the late response...

Your baud rate calculation for UART is correct.

b = φ/( V + 1 ) = 72 Mhz  / ( 4+1 )  = 14.4Mhz  ( baud rate max )

The all baud rates described in page 102, 104, 106, and 108 of CY9B110T Series datasheet are for CSIO. And, the maximum baud rate for CSIO is 8MHz.

https://www.cypress.com/file/252801/download

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