Figure 15 - Example USB to RS232 Converter ConfiguratiUSB to RS232 on
Figure 15 illustrates how to connect an FT232R as a USB to RS232 converter. A TTL – RS232 Level Converter I.C. is used on the serial UART of the FT232R to make the RS232 level conversion. This, for example can be done using the popular “213” series of TTL to RS232 level converters. These devices have 4 transmitters and 5 receivers in a 28-LD SSOP package and feature an in-built voltage converter to convert the 5V (nominal) VCC to the +/- 9 volts required by RS232. An important feature of these devices is the SHDN# pin which can power down the device to a low quiescent current during USB suspend mode.
An example of a device which can be used for this is a Sipex SP213EHCA which is capable of RS232 communication at up to 500kΩ baud. If a lower baud rate is acceptable, then several pin compatible alternatives are available such as the Sipex SP213ECA , the Maxim MAX213CAI and the Analog Devices ADM213E, which are all good for communication at up to 115,200 baud. If a higher baud rate is desired, use a Maxim MAX3245CAI part which is capable of RS232 communication at rates of up to 1M baud. The MAX3245 is not pin compatible with the 213 series devices, also its SHDN pin is active high, so connect it to PWREN# instead of SLEEP#.
In the above example CBUS0 and CBUS1 have been configured as TXLED# and RXLED#, and are being used to drive two LEDs.
Figure 15 illustrates how to connect an FT232R as a USB to RS232 converter. A TTL – RS232 Level Converter I.C. is used on the serial UART of the FT232R to make the RS232 level conversion. This, for example can be done using the popular “213” series of TTL to RS232 level converters. These devices have 4 transmitters and 5 receivers in a 28-LD SSOP package and feature an in-built voltage converter to convert the 5V (nominal) VCC to the +/- 9 volts required by RS232. An important feature of these devices is the SHDN# pin which can power down the device to a low quiescent current during USB suspend mode.
An example of a device which can be used for this is a Sipex SP213EHCA which is capable of RS232 communication at up to 500kΩ baud. If a lower baud rate is acceptable, then several pin compatible alternatives are available such as the Sipex SP213ECA , the Maxim MAX213CAI and the Analog Devices ADM213E, which are all good for communication at up to 115,200 baud. If a higher baud rate is desired, use a Maxim MAX3245CAI part which is capable of RS232 communication at rates of up to 1M baud. The MAX3245 is not pin compatible with the 213 series devices, also its SHDN pin is active high, so connect it to PWREN# instead of SLEEP#.
In the above example CBUS0 and CBUS1 have been configured as TXLED# and RXLED#, and are being used to drive two LEDs.
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