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Hello,
In the MB9B410T Series datasheet (Document Number: 002-04689 Rev. *E), page 91, concerning CSIO,
Baud rate = 8 Mbps max
Serial clock cycle time = 4tCYCP min
where "tCYCP indicates the APB bus clock cycle time"
If we consider that tCYCP min = 13.8 ns = 1/72 MHz that makes a maximum of 72/4 =18 Mbps ?
So why is the maximum specified baud rate 8 Mbps ?
Thanks in advance for your response
Gilles Carré
dipl. ing. eln.
Solved! Go to Solution.
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Thanks ShipingW_81 !
So far I understand it, max baud rate is not defined by the max frequency of the APB bus.
There must be other limitations in the hardware.
MB9B410T does have a max frequency of 72 MHz.
But with a 72 MHz frequency, the minimum value of BGR1/0 register, that is mentioned by the datasheet (Table 6-1 Reload Values and Baud Rates) is 8.
Hence the max bit rate is:
b = (72000000) / (8 + 1) = 8 Mbps according formel (1)
Conclusion, for all microcontrollers of the FM4 family the max baud rate is 8 Mbps.
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The description of CSIO Baud Rate Settings in FM4 TRM page#139 might be helpful to this topic - https://www.cypress.com/file/222976/download
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Thanks ShipingW_81 !
So far I understand it, max baud rate is not defined by the max frequency of the APB bus.
There must be other limitations in the hardware.
MB9B410T does have a max frequency of 72 MHz.
But with a 72 MHz frequency, the minimum value of BGR1/0 register, that is mentioned by the datasheet (Table 6-1 Reload Values and Baud Rates) is 8.
Hence the max bit rate is:
b = (72000000) / (8 + 1) = 8 Mbps according formel (1)
Conclusion, for all microcontrollers of the FM4 family the max baud rate is 8 Mbps.