Kontron COMe-cP2020 - Manual (Page 35)

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COMe-P2020 User Guide
35
2.5.2.8 SPI
The Serial Peripheral Interface Bus or SPI bus is a synchronous serial data link standard developed by Motorola that oper-
ates in full duplex mode. Devices communicate in master/slave mode where the master device initiates the data frame. Mul-
tiple slave devices are allowed with individual slave select (chip select) lines. Sometimes SPI is called a "four wire" serial
bus, contrasting with three, two, and one wire serial buses.
For a detailed signal description, please refer to the COM Express base specification, chapter 4.3.12.
The COMe-cP2020 supports boot from an external SPI flash. Therefore it can be configured by pin B88 (BIOS_DIS1#) for the
following configurations:
The BIOS_DIS0# signal defined in the COM-Express Base specification is not used on the COMe-cP2020.
2.5.2.9 Serial Interface
The COMe-cP2020 provides two UART interfaces which makes the following configuration possible:
• 2x 4-wire UARTs (manufacturer preset)
2.5.2.10 SMB / I2C
The COMe-cP2020 supports two I2C controllers with speeds up to 400 kHz for customer usage. The signals on the COM
Express connector labeled SMB_CK and SMB_DAT are connected to I2C controller IIC1 of the P2020. The resources occupied
for the on-board devices are as follows:
The signals on the COM Express connector labeled I2C_CK and I2C_DAT are connected to I2C controller IIC2 of the P2020.
This controller is completely dedicated to user purposes.
Table 2-8: SPI Signal Configurations
BIOS_DIS1# FUNCTION SIGNAL ROUTING
Open
Boot from on-module
flashes P2020 eSPI chip select SPI_CS2# is available
on the carrier
Pulled to GND Boot from external flash
P2020 eSPI chip select SPI_CS0# (boot chip
select) is available on the carrier
Table 2-9: On-Board Device Resource
DEVICE
I2C ADDRESS
(binary)
I2C ADDRESS
(hex)
User EEPROM 1010 110x 0xAC
System EEPROM 1010 111x 0xAE
RTC 1010 001x 0xA2
Thermal Sensor 1001 000x 0x90
SPD EEPROM 1010 000x 0xA0