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Pinout and I/O Description
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4.6.1
Typical Application
The module supports the 1-bit SD transfer mode with 3V3 signaling. An example circuit
to a 9-pin SD memory card socket is shown below. The maximum clock frequency
(SD_CLK) is 33.000 MHz.
4.6.2
Data Logging
Driving the LOGBUTTON pin low for 100 ms to 5 seconds toggles logging on and off.
Driving the LOGBUTTON pin low for more than 5 seconds and then releasing it unmounts
the SD card if it was mounted, or mounts it if it was unmounted. The SD card mount status
can be checked with the LOGLED pin (see Appendix A).
As the name suggests, the LOGBUTTON is typically interfaced to a mechanical button
(though this could also be e.g. an open-collector output or a push-pull output). The
module debounces the signal in software, so no external debouncing circuit is required.
See instructions in the Reference Guide for details on how to configure SD card logging.
The module is compatible with SD cards of up to 32GB. The file system is FAT32.
When powering off the module while logging, the last seconds of data may be lost. To
avoid data losses, it is advised to first unmount the SD card. This can be done in several
ways:
1.
By entering the command
“
exeManageDisk, DSK1, Unmount
” before turning off
the module (see the Reference Guide for a description of all the user commands).
2.
By driving the LOGBUTTON pin low for at least 5 seconds before turning off the
module.
3.
By driving the ONOFF pin low for at least 50ms. This puts the module in standby,
from where it can be safely switched off. See sections 4.12 and 5.4 for details.
