Document No.: FT_000053
FT232R USB UART IC Datasheet Version 2.07
Clearance No.: FTDI# 38
Additionally, the UART signals can each be individually inverted and have a configurable high drive
strength capability. Both these features are configurable in the EEPROM.
Baud Rate Generator - The Baud Rate Generator provides a 16x clock input to the UART Controller
from the 48MHz reference clock. It consists of a 14 bit pre-scaler and 3 register bits which provide fine
tuning of the baud rate (used to divide by a number plus a fraction or “sub-integer”). This determines the
baud rate of the UART, which is programmable from 183 baud to 3 Mbaud.
The FT232R supports all standard baud rates and non-standard baud rates from 183 Baud up to 3
Mbaud. Achievable non-standard baud rates are calculated as follows -
Baud Rate = 3000000 / (n + x)
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where „n‟ can be any integer between 2 and 16,384 ( = 2 ) and „x’ can be a sub-integer of the value 0,
0.125, 0.25, 0.375, 0.5, 0.625, 0.75, or 0.875. When n = 1, x = 0, i.e. baud rate divisors with values
between 1 and 2 are not possible.
This gives achievable baud rates in the range 183.1 baud to 3,000,000 baud. When a non-standard baud
rate is required simply pass the required baud rate value to the driver as normal, and the FTDI driver will
calculate the required divisor, and set the baud rate. See FTDI application note AN232B-05 on the FTDI
website (www.ftdichip.com) for more details.
RESET Generator - The integrated Reset Generator Cell provides a reliable power-on reset to the device
internal circuitry at power up. The RESET# input pin allows an external device to reset the FT232R.
RESET# can be tied to VCC or left unconnected if not being used.
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