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Zynq-7000 AP SoC Technical Reference Manual www.xilinx.com 596
UG585 (v1.11) September 27, 2016
Chapter 19: UART Controller
Select one of the following operating options:
Example: Automatic Flow Control
1. Set RTS trigger level. Write to the uart.Flow_Delay_reg0 register. This is the trigger level to
de-assert modem signal RTS.
2. Select automatic flow control. Write a 1 to uart.Modem_ctrl_reg0 [FCM].
3. Verify the mode change to automatic. Read uart.Modem_sts_reg0 [FCMS] until it equals 1.
When software writes a 1 to uart.Modem_ctrl_reg0 [FCM], the modem changes to automatic mode.
The change of mode from manual to automatic is verified by reading the status bit FCMS in the
Modem Status register.
Example: Manual Flow Control
1. Select manual flow control. Write a 0 to uart.Modem_ctrl_reg0 [FCM].
Option a. Control the DTR output signal using uart.Modem_ctrl_reg0 [DTR].
Option b. Control the RTS output signal using uart.Modem_ctrl_reg0 [RTS].
Example: Monitor for a Change in the DCD DSR RI CTS Flow Control Signals
A logic level change to the DCD DSR RI CTS flow control signals is detected by the controller. When
a logic level change is detected, the hardware sets the uart.Chnl_int_sts_reg0 [DMSI] bit. This change,
or channel status can optionally generate an interrupt.
1. Check flow control signal status. uart.Modem_sts_reg0 register reports the modem status.
In interrupt mode, the ISR can run when the DMSI interrupt occurs when there is a change of status
on modem lines.
19.3 Programming Guide
19.3.1 Start-up Sequence
Main Example: Start-up Sequence
1. Reset controller: The reset programming model is described in section 19.4.2 Resets.
2. Configure I/O signal routing: Rx/Tx can be routed to either MIO or EMIO. The modem control
signals are only available on the EMIO interface. Refer to section 19.5.1 MIO Programming.
3. Configure UART_Ref_Clk: The UART clock architecture and programming model are described
in section 19.4.1 Clocks.
4. Configure controller functions: Program the I/O signal characteristics and controller functions
using the uart.Control_reg0 and uart.mode_reg0 registers. Examples are shown in section
19.3.2 Configure Controller Functions.