AT91SAM7S256D-AU Atmel, AT91SAM7S256D-AU Datasheet - Page 63

• Manufacturer Part Number: AT91SAM7S256D-AU
• Description: ARM Microcontrollers - MCU 256K Flash SRAM 64K ARM based MCU
• Manufacturer: Atmel
• Series: SAM7S256r

Specifications of AT91SAM7S256D-AU

• Rohs: yes
• Core: ARM
• Processor Series: AT91SAM
• Data Bus Width: 16 bit/32 bit
• Maximum Clock Frequency: 55 MHz
• Program Memory Size: 256 KB
• Data Ram Size: 64 KB
• On-chip Adc: Yes
• Operating Supply Voltage: 3 V to 3.6 V
• Operating Temperature Range: - 40 C to + 85 C
• Package / Case: LQFP-64
• Mounting Style: SMD/SMT
• Interface Type: 2-Wire, I2S, SPI, USART
• Length: 7 mm

13.3.4.4
13.3.4.5
The Reset Controller offers several commands used to assert the different reset signals. These commands are
performed by writing the Control Register (RSTC_CR) with the following bits at 1:
The software reset is entered if at least one of these bits is set by the software. All these commands can be per-
formed independently or simultaneously. The software reset lasts Y Slow Clock cycles.
The internal reset signals are asserted as soon as the register write is performed. This is detected on the Master
Clock (MCK). They are released when the software reset is left, i.e.; synchronously to SLCK.
If EXTRST is set, the nrst_out signal is asserted depending on the programming of the field ERSTL. However, the
resulting falling edge on NRST does not lead to a User Reset.
If and only if the PROCRST bit is set, the Reset Controller reports the software status in the field RSTTYP of the
Status Register (RSTC_SR). Other Software Resets are not reported in RSTTYP.
As soon as a software operation is detected, the bit SRCMP (Software Reset Command in Progress) is set in the
Status Register (RSTC_SR). It is cleared as soon as the software reset is left. No other software reset can be per-
formed while the SRCMP bit is set, and writing any value in RSTC_CR has no effect.
Figure 13-7. Software Reset
The Watchdog Reset is entered when a watchdog fault occurs. This state lasts Y Slow Clock cycles.
When in Watchdog Reset, assertion of the reset signals depends on the WDRPROC bit in WDT_MR:
• PROCRST: Writing PROCRST at 1 resets the processor and the watchdog timer.
• PERRST: Writing PERRST at 1 resets all the embedded peripherals, including the memory system, and, in
• EXTRST: Writing EXTRST at 1 asserts low the NRST pin during a time defined by the field ERSTL in the Mode
particular, the Remap Command. The Peripheral Reset is generally used for debug purposes.
Except for Debug purposes, PERRST must always be used in conjunction with PROCRST (PERRST and
PROCRST set both at 1 simultaneously.)
Register (RSTC_MR).
Software Reset
Watchdog Reset
SRCMP in RSTC_SR
Write RSTC_CR
if PROCRST=1
periph_nreset
if PERRST=1
if EXTRST=1
proc_nreset
(nrst_out)
RSTTYP
NRST
SLCK
MCK
Freq.
Any
Any
Resynch.
1 cycle
Processor Startup
XXX
= 3 cycles
EXTERNAL RESET LENGTH
8 cycles (ERSTL=2)
0x3 = Software Reset
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
63