SAM4S16C Atmel Corporation, SAM4S16C Datasheet - Page 433

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SAM4S16C

Manufacturer Part Number
SAM4S16C
Description
Manufacturer
Atmel Corporation
Datasheets

Specifications of SAM4S16C

Flash (kbytes)
1024 Kbytes
Pin Count
100
# Of Touch Channels
32
Hardware Qtouch Acquisition
No
Max I/o Pins
79
Ext Interrupts
79
Usb Transceiver
1
Quadrature Decoder Channels
2
Usb Speed
Full Speed
Usb Interface
Device
Spi
3
Twi (i2c)
2
Uart
4
Ssc
1
Sd / Emmc
1
Graphic Lcd
No
Video Decoder
No
Camera Interface
No
Adc Channels
16
Adc Resolution (bits)
12
Adc Speed (ksps)
1000
Analog Comparators
1
Resistive Touch Screen
No
Dac Channels
2
Dac Resolution (bits)
12
Temp. Sensor
Yes
Crypto Engine
No
Sram (kbytes)
128
Self Program Memory
YES
External Bus Interface
1
Dram Memory
No
Nand Interface
Yes
Picopower
No
Temp. Range (deg C)
-40 to 85
I/o Supply Class
1.8/3.3
Operating Voltage (vcc)
1.62 to 3.6
Fpu
No
Mpu / Mmu
Yes / No
Timers
6
Output Compare Channels
6
Input Capture Channels
6
Pwm Channels
4
32khz Rtc
Yes
Calibrated Rc Oscillator
Yes
24.11 Data Float Wait States
24.11.1
11100A–ATARM–28-Oct-11
11100A–ATARM–28-Oct-11
READ_MODE
Some memory devices are slow to release the external bus. For such devices, it is necessary to
add wait states (data float wait states) after a read access:
The Data Float Output Time (t
TDF_CYCLES field of the SMC_MODE register for the corresponding chip select. The value of
TDF_CYCLES indicates the number of data float wait cycles (between 0 and 15) before the
external device releases the bus, and represents the time allowed for the data output to go to
high impedance after the memory is disabled.
Data float wait states do not delay internal memory accesses. Hence, a single access to an
external memory with long t
memory.
The data float wait states management depends on the READ_MODE and the TDF_MODE
fields of the SMC_MODE register for the corresponding chip select.
Setting the READ_MODE to 1 indicates to the SMC that the NRD signal is responsible for turn-
ing off the tri-state buffers of the external memory device. The Data Float Period then begins
after the rising edge of the NRD signal and lasts TDF_CYCLES MCK cycles.
When the read operation is controlled by the NCS signal (READ_MODE = 0), the TDF field gives
the number of MCK cycles during which the data bus remains busy after the rising edge of NCS.
Figure 24-17
assuming a data float period of 2 cycles (TDF_CYCLES = 2).
ation when controlled by NCS (READ_MODE = 0) and the TDF_CYCLES parameter equals 3.
Figure 24-17. TDF Period in NRD Controlled Read Access (TDF = 2)
• before starting a read access to a different external memory
• before starting a write access to the same device or to a different external one.
A[23:0]
D[7:0]
illustrates the Data Float Period in NRD-controlled mode (READ_MODE =1),
MCK
NRD
NCS
DF
will not slow down the execution of a program from internal
DF
) for each external memory device is programmed in the
tpacc
NRD controlled read operation
TDF = 2 clock cycles
Figure 24-18
shows the read oper-
SAM4S
SAM4S
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