SAM4S16C Atmel Corporation, SAM4S16C Datasheet - Page 678
Manufacturer Part Number
Specifications of SAM4S16C
# Of Touch Channels
Hardware Qtouch Acquisition
Max I/o Pins
Quadrature Decoder Channels
Sd / Emmc
Adc Resolution (bits)
Adc Speed (ksps)
Resistive Touch Screen
Dac Resolution (bits)
Self Program Memory
External Bus Interface
Temp. Range (deg C)
-40 to 85
I/o Supply Class
Operating Voltage (vcc)
1.62 to 3.6
Mpu / Mmu
Yes / No
Output Compare Channels
Input Capture Channels
Calibrated Rc Oscillator
Rate Generator Register (US_BRGR). The resulting clock can be provided to the SCK pin to
feed the smart card clock inputs. This means that the CLKO bit can be set in US_MR.
This clock is then divided by the value programmed in the FI_DI_RATIO field in the FI_DI_Ratio
register (US_FIDI). This is performed by the Sampling Divider, which performs a division by up
to 2047 in ISO7816 Mode. The non-integer values of the Fi/Di Ratio are not supported and the
user must program the FI_DI_RATIO field to a value as close as possible to the expected value.
The FI_DI_RATIO field resets to the value 0x174 (372 in decimal) and is the most common
divider between the ISO7816 clock and the bit rate (Fi = 372, Di = 1).
and the ISO 7816 clock.
Figure 31-5. Elementary Time Unit (ETU)
ISO7816 I/O Line
Receiver and Transmitter Control
After reset, the receiver is disabled. The user must enable the receiver by setting the RXEN bit
in the Control Register (US_CR). However, the receiver registers can be programmed before the
receiver clock is enabled.
After reset, the transmitter is disabled. The user must enable it by setting the TXEN bit in the
Control Register (US_CR). However, the transmitter registers can be programmed before being
The Receiver and the Transmitter can be enabled together or independently.
At any time, the software can perform a reset on the receiver or the transmitter of the USART by
setting the corresponding bit, RSTRX and RSTTX respectively, in the Control Register
(US_CR). The software resets clear the status flag and reset internal state machines but the
user interface configuration registers hold the value configured prior to software reset. Regard-
less of what the receiver or the transmitter is performing, the communication is immediately
The user can also independently disable the receiver or the transmitter by setting RXDIS and
TXDIS respectively in US_CR. If the receiver is disabled during a character reception, the
USART waits until the end of reception of the current character, then the reception is stopped. If
the transmitter is disabled while it is operating, the USART waits the end of transmission of both
the current character and character being stored in the Transmit Holding Register (US_THR). If
a timeguard is programmed, it is handled normally.
shows the relation between the Elementary Time Unit, corresponding to a bit time,
ISO7816 Clock Cycles