`www.thundercomm.com.
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C865 DEV KIT implements a full SPI master with 4 wires: CLK, CS, MOSI, and MISO. All signals
go directly to the SM8250 SoC. These signals are driven at 1.8 V.
4.1.5
PCM/I2S
The 96Boards specification calls for one PCM/I2S bus to be provided on the low-speed expansion
connector.
The CLK, FS, and DO signals are required while the DI is optional.
C865 DEV KIT implements a PCM/I2S with 4 wires: CLK, FS, D0~D1. The I2S signals are connected
directly to the SM8250 SoC. These signals are driven at 1.8 V.
4.1.6
Power and Reset
The 96Boards specification calls for a signal on the low-speed expansion connector that can power
on/off the board and a signal that serves as a board reset signal.
C865 DEV KIT routes the PWR_BTN_N signal to the KYP_DPWR_N pin of the PM8250 PMIC.
This signal is available on the onboard Power ON button switch (see Section 1.2.2, #20). The button
only provides an ON/Sleep function and not OFF functionality.
A mezzanine implementation of this signal should not drive it with any voltage, the only allowed
operation is to force it to GND to start the board from a sleep mode. A board shutdown will occur
when this signal is held to ground for more than 15 seconds.
C865 DEV KIT routes the RST_BTN_N (named PM_RESIN_N on the C865 DEV KIT schematic)
signal to the RESIN_N pin of the PM845 PMIC. This signal is driven by SW1302, the onboard reset
switch (see Section 1.2.2, #17). This signal is dual purpose, the default purpose is Volume down, and
the second purpose is the Reset function which needs the software configure setting.
4.1.7
Power Supplies
The 96Boards specification calls for three power rails to be present on the low-speed expansion
connector:
+1.8 V: Max of 100mA
+5 V: Able to provide a minimum of 5 W of power (1A).
SYS_DCIN: 9-18 V input with enough current to support all the board functions or the output
DCIN from onboard DC connector able to provide a minimum of 7 W of power.
C865 DEV KIT supports these requirements as follows:
+1.8 V: Driven by PMIC PM8250 VREG_S4A_1P8, which can provide 100mA.
+5 V: Driven by the 4A 5.0 V DC to DC converter. The buck can provide at least current of 2A to
