Filter
Top Products
Chapter 9 XGATE (S12XGATEV2)
MC9S12XDP512 Data Sheet, Rev. 2.11
482 Freescale Semiconductor
9.9 Initialization and Application Information
9.9.1 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.
9.9.2 Code Example (Transmit "Hello World!" on SCI)
CPU S12
;###########################################
;# SYMBOLS #
;###########################################
SCI_REGS EQU $00C8 ;SCI register space
SCIBDH EQU SCI_REGS+$00 ;SCI Baud Rate Register
SCICR2 EQU SCI_REGS+$03 ;SCI Control Register 2
SCISR1 EQU SCI_REGS+$04 ;SCI Status Register 1
SCIDRL EQU SCI_REGS+$07 ;SCI Control Register 2
TIE EQU $80 ;TIE bit mask
TE EQU $08 ;TE bit mask
RE 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 $F902
XGEM EQU $8000
XGDBGM EQU $2000
XGE EQU $0080
XGDBG EQU $0020
XGSWEIF EQU $0002