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9.7.2
System Implementation of GPIO/Interrupts
9.7.3
TCI6482 GPIO/Interrupt vs TCI100 GPIO/Interrupt
9.8
Timers
9.8.1
Configuration of Timers
9.8.2
System Implementation of Timers
Peripheral Section
It is recommended that GPIO’s used as outputs have a series resistance (22 or 33 ohms being typical
values). The value (or need) for the series resistor can be determined by simulating with the IBIS models.
If a GPIO needs to default to a particular state (low or high), an external resistor should be used. A pull-up
value of 1K is recommended to make sure that it over-rides the internal pull-down present on some
GPIOs.
GP0, GP1 and GP3 have output current ratings, Iol / Ioh, of 8mA / -8mA making them more suitable for
directly driving some LEDs as opposed to all other GP pins which have 4mA / -4mA output current ratings.
Table 21. GPIO/Interrupt Comparison: TCI6482 vs TCI100
TCI6482
TCI100
Default condition (if selected)
Disabled
Enabled
All GPIOs can generate Interrupts/EDMA
Yes
No, only GP0 and GP4-GP7
Events
Documentation for Timers:
•
TMS320TCI648x DSP 64-Bit Timer User's Guide (SPRU818)
•
TMS320C64x/C64x+ DSP CPU and Instruction Set Reference Guide (
SPRU732
)
•
Using IBIS Modes for Timing Analysis (
SPRA839
)
There are 2 timer peripherals: Timer0 and Timer1. Each timer needs to be enabled via software after a
reset before it can be used.
Each timer can be configured as a single 64--bit timer or as two 32--bit timers. There is an external timer
input signal and an external timer output signal for each timer. When a timer is used as two 32--bit timers,
the timer input and output can only be used with the lower 32-bit timer.
The timer module is clocked from CPU core clock frequency / 6. The timer input clock can be configured
to use the external timer input signal, the internal timer module clock (CPU core clock / 6) or as a gated
internal clock where the external timer input signal is used to gate the internal timer module clock.
If the external timer signals are not used, the pins can be left unconnected and the internal pull-downs will
bring the input to a low state.
In addition to the timer peripherals the CPU has a 64-bit free running counter that advances each CPU
clock after counting is enabled. The counter is accessed using two 32-bit read-only control registers in the
CPU. For more details on this timer, refer to the Time Stamp Counter Registers described in the
TMS320C64x/C64x+ DSP CPU and Instruction Set Reference Guide.
It is recommended that external timer signals use series resistance (22 or 33 ohms being typical values).
The value (or need) for the series resistor can be determined by simulating with the IBIS models.
External timer input signals are synchronized to the internal timer clock. Since the timer operates at CPU
core / 6, the timer input can be delayed from the timer input as much as one CPU core / 6 period.
SPRAAC7B – April 2006
TMS320TCI6482 Design Guide and Migration from TMS320TCI100
31
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