AT91SAM7A3-AU Atmel, AT91SAM7A3-AU Datasheet - Page 241

IC ARM7 MCU FLASH 256K 100LQFP

AT91SAM7A3-AU

Manufacturer Part Number
AT91SAM7A3-AU
Description
IC ARM7 MCU FLASH 256K 100LQFP
Manufacturer
Atmel
Series
AT91SAMr
Datasheets

Specifications of AT91SAM7A3-AU

Core Processor
ARM7
Core Size
16/32-Bit
Speed
60MHz
Connectivity
CAN, I²C, MMC, SPI, SSC, UART/USART
Peripherals
POR, PWM, WDT
Number Of I /o
62
Program Memory Size
256KB (256K x 8)
Program Memory Type
FLASH
Ram Size
32K x 8
Voltage - Supply (vcc/vdd)
1.65 V ~ 1.95 V
Data Converters
A/D 8x10b
Oscillator Type
Internal
Operating Temperature
-40°C ~ 85°C
Package / Case
100-LQFP
Controller Family/series
AT91SAM7xx
No. Of I/o's
62
Ram Memory Size
32KB
Cpu Speed
60MHz
No. Of Timers
3
Rohs Compliant
Yes
Package
100LQFP
Device Core
ARM7TDMI
Family Name
91S
Maximum Speed
60 MHz
Operating Supply Voltage
3.3 V
Data Bus Width
32 Bit
Number Of Programmable I/os
62
Interface Type
CAN/SPI/I2S/TWI/USART/USB
On-chip Adc
2(8-chx10-bit)
Number Of Timers
3
Processor Series
AT91SAMx
Core
ARM7TDMI
Data Ram Size
32 KB
Maximum Clock Frequency
60 MHz
Maximum Operating Temperature
+ 85 C
Mounting Style
SMD/SMT
3rd Party Development Tools
JTRACE-ARM-2M, MDK-ARM, RL-ARM, ULINK2
Development Tools By Supplier
AT91SAM-ICE, AT91-ISP, AT91SAM7A3-EK
Minimum Operating Temperature
- 40 C
Cpu Family
91S
Device Core Size
32b
Frequency (max)
60MHz
Total Internal Ram Size
32KB
# I/os (max)
62
Number Of Timers - General Purpose
3
Operating Supply Voltage (typ)
3.3V
Operating Supply Voltage (max)
3.6V
Operating Supply Voltage (min)
3V
Instruction Set Architecture
RISC
Operating Temp Range
-40C to 85C
Operating Temperature Classification
Industrial
Mounting
Surface Mount
Pin Count
100
Package Type
LQFP
For Use With
AT91SAM-ICE - EMULATOR FOR AT91 ARM7/ARM9AT91SAM7A3-EK - KIT EVAL FOR AT91SAM7A3
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
Eeprom Size
-
Lead Free Status / Rohs Status
 Details

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27.6.3.6
27.6.3.7
6042E–ATARM–14-Dec-06
Peripheral Deselection
Peripheral Chip Select Decoding
Fixed Peripheral Select is activated by writing the PS bit to zero in SPI_MR (Mode Register). In
this case, the current peripheral is defined by the PCS field in SPI_MR and the PCS field in the
SPI_TDR has no effect.
Variable Peripheral Select is activated by setting PS bit to one. The PCS field in SPI_TDR is
used to select the current peripheral. This means that the peripheral selection can be defined for
each new data.
The Fixed Peripheral Selection allows buffer transfers with a single peripheral. Using the PDC is
an optimal means, as the size of the data transfer between the memory and the SPI is either 8
bits or 16 bits. However, changing the peripheral selection requires the Mode Register to be
reprogrammed.
The Variable Peripheral Selection allows buffer transfers with multiple peripherals without repro-
gramming the Mode Register. Data written in SPI_TDR is 32 bits wide and defines the real data
to be transmitted and the peripheral it is destined to. Using the PDC in this mode requires 32-bit
wide buffers, with the data in the LSBs and the PCS and LASTXFER fields in the MSBs, how-
ever the SPI still controls the number of bits (8 to16) to be transferred through MISO and MOSI
lines with the chip select configuration registers. This is not the optimal means in term of mem-
ory size for the buffers, but it provides a very effective means to exchange data with several
peripherals without any intervention of the processor.
The user can program the SPI to operate with up to 15 peripherals by decoding the four Chip
Select lines, NPCS0 to NPCS3 with an external logic. This can be enabled by writing the PCS-
DEC bit at 1 in the Mode Register (SPI_MR).
When operating without decoding, the SPI makes sure that in any case only one chip select line
is activated, i.e. driven low at a time. If two bits are defined low in a PCS field, only the lowest
numbered chip select is driven low.
When operating with decoding, the SPI directly outputs the value defined by the PCS field of
either the Mode Register or the Transmit Data Register (depending on PS).
As the SPI sets a default value of 0xF on the chip select lines (i.e. all chip select lines at 1) when
not processing any transfer, only 15 peripherals can be decoded.
The SPI has only four Chip Select Registers, not 15. As a result, when decoding is activated,
each chip select defines the characteristics of up to four peripherals. As an example, SPI_CRS0
defines the characteristics of the externally decoded peripherals 0 to 3, corresponding to the
PCS values 0x0 to 0x3. Thus, the user has to make sure to connect compatible peripherals on
the decoded chip select lines 0 to 3, 4 to 7, 8 to 11 and 12 to 14.
When operating normally, as soon as the transfer of the last data written in SPI_TDR is com-
pleted, the NPCS lines all rise. This might lead to runtime error if the processor is too long in
responding to an interrupt, and thus might lead to difficulties for interfacing with some serial
peripherals requiring the chip select line to remain active during a full set of transfers.
• Fixed Peripheral Select: SPI exchanges data with only one peripheral
• Variable Peripheral Select: Data can be exchanged with more than one peripheral
AT91SAM7A3 Preliminary
241

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