Texas Instruments manual Can be generated automatically by the MSC1210

SFR Definitions

SPIRCON (SPI Receive Control, Address 9CH): This SFR is dual-purpose: when read, it will return the number of bytes currently in the SPI receive buffer; when written, it can be used to clear the receive buffer and/or indicate how many characters should accumulate in the receive buffer before triggering an SPI interrupt.

SPITCON (SPI Transmit Control, Address 9DH): This SFR, like SPIRCON,

is dual-purpose: when read, it will return the number of bytes currently in the SPI transmit buffer; when written, it can be used to clear the transmit buffer and/or configure whether the SCLK driver is enabled (when in master mode).

SPISTART (SPI Buffer Start Address, Address 9EH): This SFR indicates where the SPI buffer begins. A value of between 128 and 255 must be written to this SFR, and the buffer is situated in internal RAM in the upper 128 bytes.

SPIEND (SPI Buffer End Address, Address 9FH): This SFR indicates where the SPI buffer ends. It must be a value between 128 and 255, and must be larg- er than SPISTART.

P2 (Port 2, Address A0H, Bit-Addressable): This is input/output port 2. Each bit of this SFR corresponds to one of the pins on the microcontroller. For exam- ple, bit 0 of port 2 is pin P2.0, bit 7 is pin P2.7. Writing a value of 1 to a bit of this SFR will set a high level on the corresponding I/O pin, whereas a value of 0 will bring it to a low level.

Note:

Even though the MSC1210 has four I/O ports (P0, P1, P2, and P3), if the hardware uses external RAM or external code memory (i.e., the program is stored in an external ROM or EPROM chip, or if external RAM chips are being used), P0, P2, P3.6, or P3.7 may not used. This is because the MSC1210 uses ports P0 and P2 to address the external memory. Thus, if external RAM or code memory is being used, only P1 and P3 (except P3.6 and P3.7) are available to the application for I/O.

PWMCON (PWM Control, Address A1H): This SFR controls the PWM that

can be generated automatically by the MSC1210.

PWMLOW/PWMHIGH (PWM Low/High-Byte, Addresses A2H/A3H): This SFR works together with the PWMCON SFR to determine the length and shape of the PWM. This SFR contains the low byte.

PAI (Pending Auxiliary Interrupt, Address A5H): This SFR contains infor- mation regarding which of the various possible conditions triggered an auxilia- ry interrupt. This SFR is normally used by the ISR to determine the highest priority pending auxiliary interrupt.

AIE (Auxiliary Interrupt Enable, Address A6H): This SFR enables and disables the various interrupts that were described in the previous paragraph regarding PAI. The interrupts mentioned in PAI will only be triggered if they are enabled in this SFR and if EAI (in EICON) is enabled. When read, the AIE SFR provides the status of the interrupt, regardless of the state of the EAI bit.

Special Function Registers (SFRs) 3-9