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General-Purpose Input/Output (GPIO)
bclr
bclr
movep
movep
movep
movep
DMA requires more initialization code and consideration of DMA modes. However, it is the
most efficient use of core resources. Once these registers are programmed, you must enable
the DMA by triggering a DMA request off one of the peripheral control flags or enabling it in
normal program flow or an interrupt service routine.
5.4.4
Advantages and Disadvantages
Polling is the easiest method to implement, but it requires a large amount of DSP56303 core
processing power. The core cannot be involved in other processing activities while it is
polling receive and transmit ready bits. Interrupts require more code, but the core can process
other routines while waiting for data I/O. An interrupt is generated when data is ready to be
transferred to or from the peripheral device. DMA requires even less core intervention, and
the setup code is minimal, but the DMA channels must be available.
Note:
Do not use interrupt requests and DMA requests simultaneously.
5.5
General-Purpose Input/Output (GPIO)
The DSP56303 provides 34 bidirectional signals that can be configured as GPIO signals or as
peripheral dedicated signals. No dedicated GPIO signals are provided. All of these signals are
GPIO by default after reset. The control register settings of the DSP56303 peripherals
determine whether these signals function as GPIO or as peripheral dedicated signals. This
section describes how signals can be used as GPIO.
5-6
Example 5-3. DMA Transfers
#M_D1L0,x:M_IPRC
#M_D1L1,x:M_IPRC
#TBUFF_START,x:M_DSR1
#M_HTX,x:M_DDR1
#TBUFF_SIZE-1,x:M_DCO1
#INIT_DCR1,x:M_DCR1
DSP56303 User's Manual
; disable DMA1 interrupts
; DMA1 source is transmit buffer
; DMA1 destination is HTX
; DMA1 count is the full buffer
; init. DMA1 control register
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