timers-018
32-kHz sync
counter
sys_32k
sys_nrespwron
L4 interconnect
T32K_CLK
Public Version
www.ti.com
32-kHz Synchronized Timer
16.6 32-kHz Synchronized Timer
16.6.1 32-kHz Sync Timer Functional Description
The 32-kHz sync timer is a 32-bit counter, clocked by the falling edge of the 32-kHz system clock. It is
reset while the external asynchronous power-up reset (sys_nrespwron) primary I/O is active (main device
reset). When sys_nrespwron is released (on the rising edge of sys_nrespwron), after three 32-kHz clock
periods, the counter starts counting up from the reset value of the counter register on the falling edge of
the 32-kHz system clock. After reaching its highest value, the counter wraps back to 0 and starts counting
again.
shows the block diagram of the 32-kHz sync timer.
NOTE:
sys_nrespwron is an active low I/O.
Figure 16-18. 32-kHz Sync Timer Block Diagram
16.6.1.1 Reading the 32-kHz Sync Timer
The sync counter register is 32 bits wide and for correct count capture must be accessed as 16-bit LSB
access first and two 16-bit MSB access last. Internal synchronization logic allows reading of the counter
value while the counter is running. The time latency to read the counter is one L4 interconnect clock
period.
16.6.1.2 32-kHz Sync Timer Features
The following are the main features of the 32-kHz sync timer controller:
•
L4 slave interface support:
–
32-bit data bus width
–
32-/16-bit access supported
–
8-bit access not supported
–
16-bit address bus width
–
Burst mode not supported
–
Write nonposted transaction mode supported
•
Only read operations are supported on the module registers; no write operation is supported (no
error/no action on write).
•
Free-running 32-bit upward counter
•
Start and keep counting after power-on reset
•
Automatic roll over to 0, highest value reached (0xFFFF FFFF)
•
On-the-fly read (while counting)
16.6.2 32-kHz Sync Timer Environment
The sync timer is accessible only through the L4 interface.
2763
SWPU177N – December 2009 – Revised November 2010
Timers
Copyright © 2009–2010, Texas Instruments Incorporated
Содержание OMAP36 Series
Страница 174: ...174 List of Tables SWPU177N December 2009 Revised November 2010 Copyright 2009 2010 Texas Instruments Incorporated ...
Страница 692: ...692 MPU Subsystem SWPU177N December 2009 Revised November 2010 Copyright 2009 2010 Texas Instruments Incorporated ...
Страница 1084: ...1084 IVA2 2 Subsystem SWPU177N December 2009 Revised November 2010 Copyright 2009 2010 Texas Instruments Incorporated ...
Страница 1990: ...1990 2D 3D Graphics Accelerator SWPU177N December 2009 Revised November 2010 Copyright 2009 2010 Texas Instruments Incorporated ...
Страница 2334: ...2334 Memory Subsystem SWPU177N December 2009 Revised November 2010 Copyright 2009 2010 Texas Instruments Incorporated ...
Страница 2700: ...2700 Memory Management Units SWPU177N December 2009 Revised November 2010 Copyright 2009 2010 Texas Instruments Incorporated ...
Страница 2868: ...2868 HDQ 1 Wire SWPU177N December 2009 Revised November 2010 Copyright 2009 2010 Texas Instruments Incorporated ...
Страница 2974: ...2974 UART IrDA CIR SWPU177N December 2009 Revised November 2010 Copyright 2009 2010 Texas Instruments Incorporated ...
Страница 3054: ...3054 Multichannel SPI SWPU177N December 2009 Revised November 2010 Copyright 2009 2010 Texas Instruments Incorporated ...
Страница 3462: ...3462 MMC SD SDIO Card Interface SWPU177N December 2009 Revised November 2010 Copyright 2009 2010 Texas Instruments Incorporated ...
Страница 3508: ...3508 General Purpose Interface SWPU177N December 2009 Revised November 2010 Copyright 2009 2010 Texas Instruments Incorporated ...
Страница 3584: ...3584 Initialization SWPU177N December 2009 Revised November 2010 Copyright 2009 2010 Texas Instruments Incorporated ...
Страница 3648: ...3648 Debug and Emulation SWPU177N December 2009 Revised November 2010 Copyright 2009 2010 Texas Instruments Incorporated ...