SAM3X datasheet(27/71 Pages) ATMEL

27 / 71 page

11057BS–ATARM–13-Jul-12

SAM3X/A

11057BS–ATARM–13-Jul-12

SAM3X/A

Input/Output Lines

The SAM3X/A has different kinds of input/output (I/O) lines, such as general purpose I/Os

(GPIO) and system I/Os. GPIOs can have alternate functions thanks to multiplexing capabilities

of the PIO controllers. The same PIO line can be used whether in IO mode or by the multiplexed

peripheral. System I/Os include pins such as test pins, oscillators, erase or analog inputs.

With a few exceptions, the I/Os have input schmitt triggers. Refer to the footnotes associated

with PIOA to PIOF on page 14, at the end of Table 3-1, “Signal Description List”.

6.1

General Purpose I/O Lines (GPIO)

GPIO Lines are managed by PIO Controllers. All I/Os have several input or output modes such

as pull-up, input schmitt triggers, multi-drive (open-drain), glitch filters, debouncing or input

change interrupt. Programming of these modes is performed independently for each I/O line

through the PIO controller user interface. For more details, refer to the “PIO Controller” section

of the product datasheet.

The input output buffers of the PIO lines are supplied through VDDIO power supply rail.

The SAM3X/A embeds high speed pads able to handle up to 65 MHz for HSMCI and SPI clock

lines and 45 MHz on other lines. See product AC Characteristics for more details. Typical pull-up

value is 100 k

Ω for all I/Os.

Each I/O line also embeds an ODT (On-Die Termination), (see Figure 6-1 below). ODT consists

of an internal series resistor termination scheme for impedance matching between the driver

output (SAM3) and the PCB track impedance preventing signal reflection. The series resistor

helps to reduce IOs switching current (di/dt) thereby reducing in turn, EMI. It also decreases

overshoot and undershoot (ringing) due to inductance of interconnect between devices or

between boards. In conclusion, ODT helps reducing signal integrity issues.

Figure 6-1.

On-Die Termination

6.2

System I/O Lines

System I/O lines are pins used by oscillators, test mode, reset, flash erase and JTAG to name

but a few. Described below are the SAM3X/A system I/O lines shared with PIO lines.

These pins are software configurable as general purpose I/O or system pins. At startup, the

default function of these pins is always used.

PCB Trace

Z0 ~ 50 Ohms

Receiver

SAM3 Driver with

Rodt

Zout ~ 10 Ohms

Z0 ~ Zout + Rodt

ODT

36 Ohms Typ.

SAM3X датащи(PDF) 27 Page - ATMEL Corporation

SAM3X датащи(HTML) 27 Page - ATMEL Corporation

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71

датащи скачать

ссылки URL