
SIM225 Technical Reference Manual
© Serious Integrated, Inc.
Graphic LCD Display.................................................................................................................................................................... 23
LCD Direct Drive ...................................................................................................................................................................... 23
Touch ........................................................................................................................................................................................... 24
Power Supplies.............................................................................................................................................................................. 27
+5V_MAIN on LiPo Variants ............................................................................................................................................... 27
+5V_MAIN on Non-LiPo Variants..................................................................................................................................... 28
Main 3.3V Regulation............................................................................................................................................................ 28
Turning SIM225 Off: The PWRDWN# Signal................................................................................................................ 29
LiPo Battery................................................................................................................................................................................ 29
USB Device (“Function”) Power.......................................................................................................................................... 32
LCD Panel Backlight Power ................................................................................................................................................. 32
USB Host Power....................................................................................................................................................................... 33
Clock/Calendar Battery Power ........................................................................................................................................... 33
Memory............................................................................................................................................................................................ 34
Serial FLASH .............................................................................................................................................................................. 34
SDRAM........................................................................................................................................................................................ 34
EEPROM...................................................................................................................................................................................... 35
Serialization and Variant/Version Identification............................................................................................................... 35
Universial Serial Bus (USB)........................................................................................................................................................ 36
Device IDs................................................................................................................................................................................... 37
Software...................................................................................................................................................................................... 37
Device Port USB1..................................................................................................................................................................... 37
Embedded Host Port USB0 ................................................................................................................................................. 38
Audio ................................................................................................................................................................................................. 39
Piezo Sounder........................................................................................................................................................................... 39
DAC Outputs............................................................................................................................................................................. 39
Speaker/Amplifier ................................................................................................................................................................... 40
Temperature Sensing.................................................................................................................................................................. 40
MCU On-Chip Temperature Sensor................................................................................................................................. 40
PCB Temperature Sensor..................................................................................................................................................... 40
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