23-30
MCF5282 User’s Manual
MOTOROLA
Operation
Although the UART receive buffer is quadruple-buffered, the receiver shift register is still
shifting its characters when the DMA request is ready to read its contents; therefore, the
maximum number of data bytes read during a UART DMA request transfer is three.
When the DMA is configured for cycle steal, only one character will be transferred on a
DMA request. This mode should be used for DMA requests on FIFO not empty. DMA
requests are negated when a data byte is read from the UART receive buffer.
The UART can be configured to request service from the DMA controller on a FIFO FULL
of RxRDY condition. The steps needed to intialize DMA requests from the UART are listed
below.
1. Mask appropriate bits in IMR (bits 13-15 for UART0-UART2 respectively)
2. Initialize DMAREQC to map UART DMA Request to a DMA channel
3. Initialize DMA request in UART, see Table 23-14
23.5.6.2 UART Module Initialization Sequence
Table 23-15 shows the UART module initialization sequence.
Table 23-14. UART DMA Requests
Register
Bit
Interrupt
UMR1x
6
RxIRQ.
0 DMA request on RxRDY
1 DMA request on FIFO full
UIMRx
1
RxFIFO full will enable DMA requests
Table 23-15. UART Module Initialization Sequence
Register
Setting
UCR
n
Reset the receiver and transmitter.
Reset the mode pointer (MISC[2–0] = 0b001).
UIVR
n
Program the vector number for a UART module interrupt.
UIMR
n
Enable the preferred interrupt sources.
UACR
n
Initialize the input enable control (IEC bit).
UCSR
n
Select the receiver and transmitter clock. Use timer as source if required.
UMR1
n
If preferred, program operation of receiver ready-to-send (RxRTS bit).
Select receiver-ready or FIFO-full notification (RxRDY/FFULL bit).
Select character or block error mode (ERR bit).
Select parity mode and type (PM and PT bits).
Select number of bits per character (B/Cx bits).
UMR2
n
Select the mode of operation (CMx bits).
If preferred, program operation of transmitter ready-to-send (TxRTS).
If preferred, program operation of clear-to-send (TxCTS bit).
Select stop-bit length (SBx bits).
UCR
Summary of Contents for ColdFire MCF5281
Page 124: ...3 20 MCF5282 User s Manual MOTOROLA EMAC Instruction Set Summary ...
Page 141: ...MOTOROLA Chapter 5 Static RAM SRAM 5 5 SRAM Programming Model ...
Page 142: ...5 6 MCF5282 User s Manual MOTOROLA SRAM Programming Model ...
Page 168: ...6 26 MCF5282 User s Manual MOTOROLA Interrupts ...
Page 186: ...7 18 MCF5282 User s Manual MOTOROLA Functional Description ...
Page 228: ...9 22 MCF5282 User s Manual MOTOROLA Functional Description ...
Page 246: ...10 18 MCF5282 User s Manual MOTOROLA Low Power Wakeup Operation ...
Page 254: ...11 8 MCF5282 User s Manual MOTOROLA Memory Map and Registers ...
Page 264: ...12 10 MCF5282 User s Manual MOTOROLA Chip Select Registers ...
Page 280: ...13 16 MCF5282 User s Manual MOTOROLA Misaligned Operands ...
Page 314: ...14 34 MCF5282 User s Manual MOTOROLA MCF5282 External Signals ...
Page 339: ...MOTOROLA Chapter 15 Synchronous DRAM Controller Module 15 25 SDRAM Example ...
Page 340: ...15 26 MCF5282 User s Manual MOTOROLA SDRAM Example ...
Page 356: ...16 16 MCF5282 User s Manual MOTOROLA DMA Controller Module Functional Description ...
Page 408: ...17 52 MCF5282 User s Manual MOTOROLA Buffer Descriptors ...
Page 446: ...20 24 MCF5282 User s Manual MOTOROLA Interrupts ...
Page 474: ...22 18 MCF5282 User s Manual MOTOROLA Programming Model ...
Page 510: ...23 36 MCF5282 User s Manual MOTOROLA Operation ...
Page 526: ...24 16 MCF5282 User s Manual MOTOROLA I2C Programming Examples ...
Page 672: ...28 12 MCF5282 User s Manual MOTOROLA Functional Description ...
Page 718: ...29 46 MCF5282 User s Manual MOTOROLA Motorola Recommended BDM Pinout ...
Page 750: ...32 8 MCF5282 User s Manual MOTOROLA Ordering Information ...