User manual
Table Of Contents
- Zynq-7000 All Programmable SoC
- Table of Contents
- Ch. 1: Introduction
- Ch. 2: Signals, Interfaces, and Pins
- Ch. 3: Application Processing Unit
- Ch. 4: System Addresses
- Ch. 5: Interconnect
- Ch. 6: Boot and Configuration
- Ch. 7: Interrupts
- Ch. 8: Timers
- Ch. 9: DMA Controller
- Introduction
- Functional Description
- DMA Transfers on the AXI Interconnect
- AXI Transaction Considerations
- DMA Manager
- Multi-channel Data FIFO (MFIFO)
- Memory-to-Memory Transfers
- PL Peripheral AXI Transactions
- PL Peripheral Request Interface
- PL Peripheral - Length Managed by PL Peripheral
- PL Peripheral - Length Managed by DMAC
- Events and Interrupts
- Aborts
- Security
- IP Configuration Options
- Programming Guide for DMA Controller
- Programming Guide for DMA Engine
- Programming Restrictions
- System Functions
- I/O Interface
- Ch. 10: DDR Memory Controller
- Introduction
- AXI Memory Port Interface (DDRI)
- DDR Core and Transaction Scheduler (DDRC)
- DDRC Arbitration
- Controller PHY (DDRP)
- Initialization and Calibration
- DDR Clock Initialization
- DDR IOB Impedance Calibration
- DDR IOB Configuration
- DDR Controller Register Programming
- DRAM Reset and Initialization
- DRAM Input Impedance (ODT) Calibration
- DRAM Output Impedance (RON) Calibration
- DRAM Training
- Write Data Eye Adjustment
- Alternatives to Automatic DRAM Training
- DRAM Write Latency Restriction
- Register Overview
- Error Correction Code (ECC)
- Programming Model
- Ch. 11: Static Memory Controller
- Ch. 12: Quad-SPI Flash Controller
- Ch. 13: SD/SDIO Controller
- Ch. 14: General Purpose I/O (GPIO)
- Ch. 15: USB Host, Device, and OTG Controller
- Introduction
- Functional Description
- Programming Overview and Reference
- Device Mode Control
- Device Endpoint Data Structures
- Device Endpoint Packet Operational Model
- Device Endpoint Descriptor Reference
- Programming Guide for Device Controller
- Programming Guide for Device Endpoint Data Structures
- Host Mode Data Structures
- EHCI Implementation
- Host Data Structures Reference
- Programming Guide for Host Controller
- OTG Description and Reference
- System Functions
- I/O Interfaces
- Ch. 16: Gigabit Ethernet Controller
- Ch. 17: SPI Controller
- Ch. 18: CAN Controller
- Ch. 19: UART Controller
- Ch. 20: I2C Controller
- Ch. 21: Programmable Logic Description
- Ch. 22: Programmable Logic Design Guide
- Ch. 23: Programmable Logic Test and Debug
- Ch. 24: Power Management
- Ch. 25: Clocks
- Ch. 26: Reset System
- Ch. 27: JTAG and DAP Subsystem
- Ch. 28: System Test and Debug
- Ch. 29: On-Chip Memory (OCM)
- Ch. 30: XADC Interface
- Ch. 31: PCI Express
- Ch. 32: Device Secure Boot
- Appx. A: Additional Resources
- Appx. B: Register Details
- Overview
- Acronyms
- Module Summary
- AXI_HP Interface (AFI) (axi_hp)
- CAN Controller (can)
- DDR Memory Controller (ddrc)
- CoreSight Cross Trigger Interface (cti)
- Performance Monitor Unit (cortexa9_pmu)
- CoreSight Program Trace Macrocell (ptm)
- Debug Access Port (dap)
- CoreSight Embedded Trace Buffer (etb)
- PL Fabric Trace Monitor (ftm)
- CoreSight Trace Funnel (funnel)
- CoreSight Intstrumentation Trace Macrocell (itm)
- CoreSight Trace Packet Output (tpiu)
- Device Configuration Interface (devcfg)
- DMA Controller (dmac)
- Gigabit Ethernet Controller (GEM)
- General Purpose I/O (gpio)
- Interconnect QoS (qos301)
- NIC301 Address Region Control (nic301_addr_region_ctrl_registers)
- I2C Controller (IIC)
- L2 Cache (L2Cpl310)
- Application Processing Unit (mpcore)
- On-Chip Memory (ocm)
- Quad-SPI Flash Controller (qspi)
- SD Controller (sdio)
- System Level Control Registers (slcr)
- Static Memory Controller (pl353)
- SPI Controller (SPI)
- System Watchdog Timer (swdt)
- Triple Timer Counter (ttc)
- UART Controller (UART)
- USB Controller (usb)
Zynq-7000 AP SoC Technical Reference Manual www.xilinx.com 595
UG585 (v1.11) September 27, 2016
Chapter 19: UART Controller
In automatic flow control mode the request to send output is asserted and de-asserted based on the
current fill level of the receiver FIFO, which results in the far-end transmitter pausing transmission
and preventing an overflow of the UART receiver FIFO. The FDEL field in the Flow Delay register
(Flow_delay_reg0) is used to setup a trigger level on the Receiver FIFO which causes the de-assertion
of the request to send. It remains Low until the FIFO level has dropped to below four less than FDEL.
Additionally in automatic flow control mode, the UART only transmits while the clear to send input
is asserted. When the clear to send is de-asserted, the UART pauses transmission at the next
character boundary.
If flow control is selected as automatic, then Flow Delay register must be programmed in order to
have a control on the inflow of data, which is done by de-asserting RTS signal. The value corresponds
to the RxFIFO level at which RTS signal will be de-asserted. It will be re-asserted when the RxFIFO
level drops to four below the value programmed in the Flow Delay register.
The uart.Channel_sts_reg0 [FDELT] register bit is used to monitor the RxFIFO level in comparison with
the flow delay trigger level. The [FDELT] bit is set whenever the RxFIFO level is greater than or equal
to trigger the level programmed in the Flow Delay register.
The trigger level programmed in the Flow Delay register has no dependency on the Rx Trigger Level
register. This is to only control the inflow of data using the RTS modem signal.
The CPU will be interrupted by receive data only on receipt of an Rx Trigger interrupt. Data is
retrieved based on the trigger level programmed in the Rx Trigger Level register.
Programmable Parameters
The UART flow control signals, DTR and RTS are generated by the UART controller.
• The RTS flow control signal is used to signal for Rx (ready to send signal to the attached
terminal).
• The DTR flow control signal indicates the status of the UART controller (data terminal ready).
The DTR and RTS can be controlled manually by software or automatically by the controller.
• In automatic mode, the modem control unit asserts and de-asserts the RTS and DTR signals.
• In manual mode, software controls the RTS and DTR signals using uart.Modem_ctrl_reg0.
uart.Modem_ctrl_reg0:
• [DTR]: Data Terminal Ready output signal
• [RTS]: Request to Send output signal
• [FCM]: Select Automatic or Manual flow control.
uart.Modem_sts_reg0:
• [DCTS]: Delta Clear To Send (input) status
• [DDSR]: Delta Data Set Ready (input) status
• [TERI]: Trailing-edge Ring Indicator (input) status
• [DDCD]: Delta Data Carrier Detect (input) status