Uart Power; Uart Data Pins - Psion Teklogix OMNii HDK XT10 User Manual

There are two headers on the board for serial interfaces: one standard RS-232 DE9 serial
connector (J30), and one 6-pin in-line connector for custom UART connections (J11). Both
connectors support serial communications at data rates up to 115200 Kbps.
9.7.1 RS-232 / UART Power
Power for the RS-232 interface is provided by the EXP_3V3 power line from Omnii. When the
breakout board is connected to Omnii, power is automatically supplied to this port.
Power for devices connected to the custom UART connector is provided by VSYS power from
Omnii. Power converters on the breakout board split the VSYS power into 3.3 V (HDK_3V3) and
5 V (HDK_5V0) lines.
The UART header on the breakout board can draw power from either the 3.3 V or 5 V lines, but
not both at the same time. These power lines must first be enabled by installing jumpers across the
pins of jumper headers J38, J37, and J3 (see Section 9.5: "Power Configuration" for more details).
After the power lines are enabled, select the UART voltage by installing a jumper on jumper
header J15 as indicated in the following table:
Table 9.6 UART Power Jumper J15 Settings
Position
1-2 UART 3.3 V Power
2-3 UART 5 V Power
Figure 9.14 UART Power Jumper J15 Pin Order
9.7.2 RS-232 / UART Data Pins
The expansion ports on Omnii use common data pins for connecting to GPIO, RS-232 / UART
and SPI devices. In addition to configuring the pins on Omnii for the specific type of device being
attached to the expansion port (see PinFunctions registry entry in Section 4.4.1 on page 26), the
breakout board must also be configured to direct the data pins to the correct header.
Configuring the data pins for a serial connection is done in two stages. First, the pins must be
directed between GPIO and serial function, using jumpers J16-J19. Next, having established serial
connectivity, the data pins must be routed to either the standard RS-232 port (J30) or the custom
inline UART connector (J11) using jumpers J20-J23.
Data lines for full modem support are also provided and are similarly configured in two stages.
First, set jumpers J24-J27 to indicate GPIO and RS-232 functions. Next, use jumpers J43-J46 to
select the modem signals.
Function
1 2 3
Psion Teklogix Omnii HDK User Manual
Chapter 9: Breakout Board
RS-232 / UART Power
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