beautypg.com

General purpose i/o (gpio), Booting from external rom, Booting via spi – Siemens ERTEC200 User Manual

Page 35: Booting via uart, Booting via lbu, Memory swapping, Table 8: selection of download source, 2 general purpose i/o (gpio)

background image

4.2 General Purpose I/O (GPIO)

Up to 45 General Purpose Inputs/Outputs are available in the ERTEC 200. These are divided into two groups:

GPIO[31:0]

32 bits on the APB I/O bus

GPIO[44:32]

13 bits as an alternative function on the LBU interface

The GPIOs [31 : 0] can be used as follows

• Inputs

• Outputs

One of up to 3 additional special functions (Watchdog, Timer, F-Timer, UART, SPI, ETM and MC-PLL)


The direction of the IO can be programmed bit-by-bit in the "GPIO_IOCTRL“ register.

The function selection of the special I/O functions can be programmed in the GPIO_PORT_MODE_L

a

nd

GPIO_PORT_MODE_H registers.
The GPIO inputs [1 : 0] and [31 : 30] can also be used as external interrupt inputs. They are connected at the IRQ
interrupt controller of the ARM946. The polarity of the GPIO interrupts can be specified with the GPIO_POLSEL register
(see GPIO register description)

The following figure shows the structure of a GPIO[31 : 0] pin as a normal I/O function or as an alternative function.

GPIO(i)

GPIO

IN

GPIO

OUT (i)

Alternate function 1,2,3 (if input)

Alternate function 1,2,3 (if output)

GPIO

IOCTRL(i)

GPIO_PORT

MODE_L&..._H

(2*i+1, 2*i)

Pin of

ERTEC200

Figure 4: GPIO Cell on GPIO Port [31:0] of the ERTEC 200

The GPIOs [44 : 32] are available on the LBU bus when the LBU interface is not used. The selection is made with the
configuration pin CONFIG[2] = 1. The GPIOs[44:32] can then be used as normal inputs or outputs. The direction of the
GPIOs[44:32] can be programmed bit-by-bit in the "GPIO_IOCTRL2“ register.


Copyright © Siemens AG 2007. All rights reserved.

35

ERTEC 200 Manual

Technical data subject to change Version 1.1.0