Kontron COMe-cP2020 Uživatelský manuál stáhnout pdf (Strana 57)

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COMe-P2020 User Guide

• POST Mode: LEDs build a binary vector to display POST code during the pre-boot phase. In doing so, the higher 4-bit

nibble of the 8-bit POST code is displayed followed by the lower nibble followed by a pause.

• Mode A: LEDs controlled by CPU

Beside the configurable functions described above the LEDs fulfill also a basic debug function during the power up phase as

long as the first access to POST Code LOW Byte Register (0x080) is processed. If a LED lights red and stays red, then a basic

error is present on the board.

The following debug functions are defined and displayed during this initialization phase:

• LED3: PGOOD failure, Power Good status not reached

• LED2: not used

• LED1: CPU reset is asserted/not asserted

• LED0: U-Boot boot failure

Table 3-37: 0x290: LED Configuration Register

ACTION D7 D6 D5 D4 D3 D2 D1 D0

READ0000 LCON

WRITENUNUNUNU LCON

POWER UP 0 0 0 0 0000

BITFIELD DESCRIPTION

[D0-D3] LCON Use specific LED configuration:

"0000" = POST

"0001" = Mode A (General Purpose Mode)

others = Reserved

Table 3-38: 0x291: LED Control Register

ACTION D7 D6 D5 D4 D3 D2 D1 D0

READ 0000 LED3 LED2 LED1 LED0

WRITE NU LED3 LED2 LED1 LED0

POWER UP 0000 0 0 0 0

BITFIELD DESCRIPTION

[D0] LED0 LED Control Register, controls Board LED D5:

'0' = LED is OFF

'1' = LED is ON

[D1] LED1 LED Control Register, controls Board LED D6:

'0' = LED is OFF

'1' = LED is ON

[D2] LED2 LED Control Register, controls Board LED D7:

'0' = LED is OFF

'1' = LED is ON

[D3] LED3 LED Control Register, controls Board LED D3:

'0' = LED is OFF

'1' = LED is ON

1 2 ... 52 53 54 55 56 57 58 59 60 61 62 ... 105 106

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Kontron COMe-cP2020 Uživatelský manuál Strana 57