PC912XDP512F0CALR datasheet(291/1348 Pages) FREESCALE

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Chapter 6 XGATE (S12XGATEV2)

MC9S12XDP512 Data Sheet, Rev. 2.21

Freescale Semiconductor

291

6.9

Initialization and Application Information

6.9.1

Initialization

The recommended initialization of the XGATE is as follows:

1. Clear the XGE bit to suppress any incoming service requests.

2. Make sure that no thread is running on the XGATE. This can be done in several ways:

a) Poll the XGCHID register until it reads $00. Also poll XGDBG and XGSWEIF to make sure

that the XGATE has not been stopped.

b) Enter Debug Mode by setting the XGDBG bit. Clear the XGCHID register. Clear the XGDBG

bit.

The recommended method is a).

3. Set the XGVBR register to the lowest address of the XGATE vector space.

4. Clear all Channel ID ﬂags.

5. Copy XGATE vectors and code into the RAM.

6. Initialize the S12X_INT module.

7. Enable the XGATE by setting the XGE bit.

The following code example implements the XGATE initialization sequence.

6.9.2

Code Example (Transmit "Hello World!" on SCI)

CPU

S12X

;###########################################

SYMBOLS

;###########################################

SCI_REGS

EQU

$00C8

;SCI register space

SCIBDH

EQU

SCI_REGS+$00

;SCI Baud Rate Register

SCIBDL

EQU

SCI_REGS+$00

;SCI Baud Rate Register

SCICR2

EQU

SCI_REGS+$03

;SCI Control Register 2

SCISR1

EQU

SCI_REGS+$04

;SCI Status

SCIDRL

EQU

SCI_REGS+$07

;SCI Control Register 2

TIE

EQU

$80

;TIE bit mask

EQU

$08

;TE bit mask

EQU

$04

;RE bit mask

SCI_VEC

EQU

$D6

;SCI vector number

INT_REGS

EQU

$0120

;S12X_INT register space

INT_CFADDR

EQU

INT_REGS+$07

;Interrupt Configuration Address Register

INT_CFDATA

EQU

INT_REGS+$08

;Interrupt Configuration Data Registers

RQST

EQU

$80

;RQST bit mask

XGATE_REGS

EQU

$0380

;XGATE register space

XGMCTL

EQU

XGATE_REGS+$00

;XGATE Module Control Register

XGMCTL_CLEAR

EQU

$FA02

;Clear all XGMCTL bits

XGMCTL_ENABLE

EQU

$8282

;Enable XGATE

XGCHID

EQU

XGATE_REGS+$02

;XGATE Channel ID Register

XGVBR

EQU

XGATE_REGS+$06

;XGATE ISP Select Register

XGIF

EQU

XGATE_REGS+$08

;XGATE Interrupt Flag Vector

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