User manual

6 OnRISC Hardware API
6.4.2. OMAP3 based Devices
Serial interfaces on OMAP3 devices use FTDI USB-to-serial converter chips (FT2232D). Both ports
appear in the system as /dev/ttyUSB0 and /dev/ttyUSB1. Two methods are provided to switch
between RS232/RS422/RS485 modes (termination inclusive): via software
48
and via DIP-switch.
Each port has its own DIP-switch named SW1 and SW2. Table 5 shows possible DIP-switch
settings.
S1 S2 S3 S4 Mode
off off x x RS-232 Loopback Test
on off x x RS-232 MODE
on on on off RS-422 MODE
on on on on RS-422 MODE RxD +/- with 120 ohm Term
on on off off RS-485 Full Duplex Mode
on on off on RS-485 Full Duplex Mode RxD +/- with 120 ohm Term
off on off off RS-485 Half Duplex Mode without Echo
off on off on RS-485 Half Duplex Mode without Echo RxD +/- with 120 ohm Term
Table 5: Serial Modes (hardware switching)
48
Refer to Section B.1 for software method.
May 2014 OnRISC User Manual 45