10. Clocks, Resets and Power-up Options > Resets
209
Tsi578 User Manual
June 6, 2016
Integrated Device Technology
www.idt.com
10.2
Resets
Internal logic is responsible for automatically sequencing the removal of reset in all internal blocks to
meet their requirements; no additional software programming is required.
10.2.1
Device Reset
The Tsi578 can be reset the following ways:
1.
Assertion of the HARD_RST_b input pin
2.
Receiving four RapidIO Link Request/Reset-Device Control Symbols in a row (without any other
intervening packets or control symbols, except status control symbols) from any of the RapidIO
ports.
•
“RapidIO Port x Mode CSR” on page 310
must be set to 1
(self-reset)
In both cases, when the Tsi578 is reset it goes through its full reset and power-up sequence. All state
machines and the configuration registers are reset to the original power on states.
10.2.1.1
I
2
C Boot
When all blocks have been taken out of reset, the I
2
C Interface is responsible for performing automatic
reads from an externally attached EEPROM device in order to load the initial configuration of the
device. For more details refer to
10.2.1.2
HARD_RST_b Reset
The HARD_RST_b signal is an external system reset input signal and causes a general reset of the
Tsi578; all blocks are reset within the device. HARD_RST_b is an active low signal with asynchronous
assertion and de-assertion. The internal reset synchronizers are responsible for assuring that reset is
de-asserted internally at the correct time for each of the clock domains.
When HARD_RST_b is asserted, SW_RST_b is de-asserted. SW_RST_b remains de-asserted after
HARD_RST_b is released.
Lookup tables are left in an undefined state after reset. It is recommended that lookup tables
be completely initialized after a reset to ensure deterministic operation.
External I
2
C devices are not reset by the Tsi578, so the I
2
C bus could be left in an undefined
state if the Tsi578 is reset during initial configuration. It is recommended that resets of the
Tsi578 occur at a rate that ensures that register loading from I
2
C device has completed before
another reset is issued.