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DIMM.AM335x (Rev3) 14/24

The LED is controlled by the two GPIO pins of the AM335x. Pin GPIO2_4 drives the green LED, pin

GPIO2_5 drives the red LED. Watch that the green LED is active low while the red LED is active high.

This gives the following colour table:

LED

GPIO2_4

GPIO2_5

green

yellow

off

red

3.18 RTC

The current consumption of the integrated RTC of the CPU is too high to be buffered by a battery.

Therefore an external RTC RX-8025 from Epson is added. This RTC has a current consumption of

about 0.5 µA and is buffered by an external battery connected to the BAT pin of the SODIMM

connector.

While the board is powered the 32 kHz clock of the RTC is connected to the CPU. Therefore the

time information can be copied at power on from the Epson RTC to the integrated RTC of the

processor and both count with the same clock source.

The RTC RX-8025 is connected to the I²C interface and uses the 7 bit address 0x32.

The frequency precision of the RTC is given with 5 +/-5 ppm at 25°C and a maximum deviation of

+10 / -120ppm over the temperature range -20°C …+70°C.

3.19 Reset

There are several ways to reset the board:

 The PMIC supervises all voltages and causes a power on reset in undervoltage situations

 A low pulse at pin RESI# of the SODIMM connector causes a power on reset

 Setting the PRM_RSTCTRL.RST_GLOBAL_COLD_SW bit in the PRM memory map causes a

power on reset. This bit is self-clearing; it is automatically cleared by the hardware.

 A low signal at pin CSRSTZ# of the Debug connector causes a warm reset

All resets also reset the Ethernet PHY and the Flash interface. Also the reset signal is driven to the

pin RESO# at the SODIMM connector to reset external devices.

3.20 Power Supply, PMIC

The maximum power consumption of the module DIMM-AM335x is 0.6 A at +3.3 V, +/- 5%. This

voltage must be supplied via the SODIMM connector. All further voltages needed are generated

on board by the power management controller (PMIC) TPS65910A3 from Texas Instruments [2].

The PMIC generates all voltages and cares about the appropriate voltage sequencing at power up

and down. The voltages can be controlled by the processor AM335x via an I²C interface. The PMIC

incorporates two interfaces with the 7-bit I²C addresses 0x12 and 0x2D.

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Epson Powerspan Manuale Utente Pagina 14