STLC4420A datasheet(30/40 Pages) STMICROELECTRONICS

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Registers description

STLC4420A

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Registers description

5.1

ARM interrupt register

The HOSTMSG bits of this register are written by the Host and generate interrupts to the

ARM processor when the corresponding bit is set in the ARM Interrupt Enable register.

Writing a logic 1 causes the corresponding interrupt bit to be set. All other bits are

unaffected; previously set bits will remain set. This register can be read/written while the

device is in sleep Mode (i.e. running off the low frequency oscillator) and not generate an

ARM_asleep interrupt.

Note:

Both the ARM and Host Interrupt Register have the bit "ARM_ASLEEP". Although only the

host generates this bit it is used as an interrupt source to both. When the Host sees this

interrupt, it is expected that it will poll the device control/status Register until the SleepMode

status bit is de-asserted by ARM before continuing.

The format of the register is defined in Table 7.

5.2

ARM interrupt acknowledge

This register is written by the ARM processor and clears bits in the ARM interrupt register.

Writing a logic 1 in any bit position causes the corresponding interrupt bit to be cleared. All

other bits are unaffected.

The format of the register is defined in Table 8.

Table 7.

ARM interrupt register

Bit position

Name

Description

ARM_ASLEEP

Indicates that an access to hardware registers or device memory

(by Host) was attempted while the device was in sleep-mode.

DMA wr done

Last Write Occurred

DMA rd done

Last Read Occurred

DMA rd ready

DMA rd FIFO ready to be read

27:16

Reserved

Not Implemented

15:0

HOSTMSG

General purpose Host Message Interrupts. May be written by

the Host to cause an interrupt to the ARM Processor.

Table 8.

ARM interrupt acknowledge

Bit position

Name

Description

ARM_ASLEEP

Indicates that an access to hardware registers or device memory

(by Host) was attempted while the device was in sleep-mode.

DMA wr done

Last Write Occurred

DMA rd done

Last Read Occurred

DMA rd ready

DMA rd FIFO ready to be read

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