SDA55XX Datasheet, PDF (105/230 Pages) Infineon Technologies AG – Preliminary & Confidential

SDA 55xx
Preliminary & Confidential
9
Reset
Reset
9.1
Reset sources
TVText Pro can be reset by two sources.
1) Externally by pulling down the reset pin RST .
2) Internally by Watch dog timer reset.
Note that both the reset signals use the same path however Watchdog reset doesnot
reset the PLL.
9.2
Reset filtering
RST pin uses a filterwith delay element , which suppresses the jitter and spikes in the
range of 25 nsec to 75 nsec.
9.3
Reset duration
With the active edge of the RST an internal signal resets all the flip flops asynchrounsly.
The internal signal is released synchronusly to the internal clock when it is stable as
described below.
Duration of the external reset depends on the time required for crystal oscilator to
stablize and is dependend on the crystal used.
During the period when the RST pin is held low, the PLL is initialized and it gets locked.
The high going reset pulse then initiates a sequence which requires one machine cycle
(12 clock cycles) to initialize the processor and all other registers and peripherals.
9.4
Registers
Upon reset, all the registers are initialized to the values as defined in Register overview
chapter.
9.5
Functional blocks
All the blocks to a known a known state. Processor, Acquisiton and display will not have
any pending bus requests after reset.
9.6
RAMs
Reset hardware does not intialize any RAMs.
Semiconductor Group
105
User’s Manual July 99