QSEVEN-Q7ALx2 - Preliminary User Guide, Rev. 0.7
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RTC
6.8.
The Real Time Clock (RTC) accurately keeps track of the current time. The RTC’s low power consumption means that
the RTC can be powered from an alternative source of power, enabling the RTC to continue to keep time while the
primary source of power is off or unavailable. The Q7ALx2 module’s RTC battery voltage range is 2.4 V - 3.3 V.
SDIO
6.9.
The Secure Digital Input/Output (SDIO) interface is used to interchange data between devices. Using an SDIO card,
data can be interchanged between portable or non-portable memory. The 4-bit SDIO transmits data on SDIO_DAT1
(pin 148), SDIO_DAT1 (pin 149), SDIO_DAT3 (pin 149) and SDIO_DAT4 (pin 150) and controls the data using pins 142,
143, 145, 146 and 147 on the Qseven® connector.
SPI
6.10.
The Serial Peripheral Interface Bus (SPI) bus is a synchronous four-wire serial data link standard. Devices
communicate in master/slave mode, where the master device initiates the data frame. .A master device can control
one or multiple slave device(s) by setting the slave’s (chip select) line.
The Q7ALx2 module supports one fast Serial Peripheral Interface Bus (SPI) interface. The SPI interface is connected to
the primary SPI chip on the module and can also be used to boot from the external BIOS SPI chip on the carrier board.
The SPI interface can boot from the primary on-module SPI chip or with an external SPI BIOS
chip on the carrier board.
6.10.1.
SPI boot
SPI boot is perfomed from the module’s 128 Mb SPI Flash used for BIOS storage or the carrier board’s Flash pin
(Module_BIOS_DIS#).
Table 9: SPI Boot Pin Configuration
Configuration
MODULE_BIOS_DIS#
Function
1
Open
Boot on module BIOS
2
GND
Boot on carrier board BIOS
The BIOS does not support being split between two chips. Booting takes place either from
the module SPI or from the carrier board SPI.
