ADSP-BF50x Blackfin Processor Hardware Reference
21-11
Removable Storage Interface
In order to stop the signals from floating when no card is inserted or dur-
ing times when all card drivers are in a high-impedance mode, various
pull-up and pull-down resistor configurations can be enabled on the
RSI_DATAx
signals. The
RSI_CONFIG
register (see
“RSI Configuration Reg-
ister (RSI_CONFIG)” on page 21-78
) allows for the following options:
• Enable or disable a pull-down resistor on the
RSI_DATA3
signal
• Enable or disable a pull-up resistor on the
RSI_DATA3
signal
• Enable or disable pull-up resistors on the
RSI_DATA7
through
RSI_DATA4
,
RSI_DATA2
through
RSI_DATA0
signals and the
RSI_CMD
signal
Card Detection
The RSI allows for software to detect when a card is inserted into its slot.
There are a number of ways that this card detection can be performed.
SD and SDIO cards use an internal pull-up resistor on the
RSI_DATA3
line
as a card detect signal to indicate to the host that a card is present. In
order to use the
RSI_DATA3
signal for card detection, an external
pull-down resistor should be added to the pin in order to pull the pin low
during the time a card is not inserted. When a card is inserted into the
slot, a rising edge is detected on
RSI_DATA3
by the RSI and
SD_CARD_DET
is
set within the
RSI_ESTAT
register. Once the card has been correctly identi-
fied, the
SD_CARD_DET
interrupt should be cleared and disabled then the
pull-up resistor within the SD card should be disabled by issuing the
SET_CLR_CARD_DETECT
command.
When using the
RSI_DATA3
signal for card detection with an exter-
nal pull-down resistor, do not enable the internal pull-up resistor
by setting
PU_DAT3
.
The recommended method of detecting the insertion of a card is to use
the card detect feature that is made available through most sockets.
Summary of Contents for EZ-KIT Lite ADSP-BF506F
Page 50: ...Contents l ADSP BF50x Blackfin Processor Hardware Reference ...
Page 92: ...Development Tools 1 30 ADSP BF50x Blackfin Processor Hardware Reference ...
Page 110: ...Interface Overview 3 12 ADSP BF50x Blackfin Processor Hardware Reference ...
Page 236: ...Internal Flash Memory Control Registers 6 92 ADSP BF50x Blackfin Processor Hardware Reference ...
Page 650: ...Programming Examples 15 56 ADSP BF50x Blackfin Processor Hardware Reference ...
Page 804: ...Programming Examples 17 92 ADSP BF50x Blackfin Processor Hardware Reference ...
Page 1194: ...Programming Examples 24 90 ADSP BF50x Blackfin Processor Hardware Reference ...
Page 1256: ...ACM Registers A 50 ADSP BF50x Blackfin Processor Hardware Reference ...
Page 1264: ...Boundary Scan Architecture B 8 ADSP BF50x Blackfin Processor Hardware Reference ...