Maxim-integrated MAXQ622 Bedienungsanleitung PDF herunterladen (Seite 94)

MAXQ612/MAXQ622 User’s Guide

Maxim Integrated 5-21

SBUF1 (03h, 03h) Serial Data Buffer 1

Initialization: This buffer is cleared to 00h on all forms of reset.

Read/Write Access: Unrestricted read/write.

SBUF1.7 to SBUF1.0 Serial Data Buffer 1 Bit 7:0. Data for serial port 0 is read from or written to this location.

The serial transmit and receive buffers are separate but both are addressed at this location.

SPIB0 (04h, 03h) SPI Data Buffer 0 (16-bit register)

Initialization: This buffer is cleared to 0000h on all forms of reset.

Read/Write Access: Unrestricted read, write is allowed outside of a transfer cycle; when the STBY bit is set, write

is blocked and causes write collision error.

SPIB0.15 to SPIB0.0 SPI Data Buffer 0 Bits 15:0. Data for SPI is read from or written to this location. The serial

transmit and receive buffers are separate but both are addressed at this location.

SPICN0 (05h, 03h) SPI Control Register 0

Initialization: This buffer is cleared to 00h on all forms of reset.

Read/Write Access: Unrestricted read/write except bit 7 is read-only.

SPICN0.0 (SPIEN) SPI Enable. Setting this bit to 1 enables the SPI module and its baud-rate generator for SPI

operation. Clearing this bit to 0 disables the SPI module and its baud-rate generator.

SPICN0.1 (MSTM) Master Mode Enable. MSTM functions as a master mode enable bit for the SPI module.

When MSTM is set to 1, the SPI operates as a master. When MSTM is cleared to 0, the

SPI module operates in slave mode. Note that this bit can be set from 0 to 1 only when the

SSEL signal is deasserted.

SPICN0.2 (MODFE)

Mode Fault Enable. When set to 1 in master mode, this bit enables the use of SSEL input

as a mode fault signal; when cleared to 0, the SSEL has no function and its port pin can be

used for other purposes. In slave mode, the SSEL pin always functions as a slave select

input signal to the SPI module, independent of the setting of the MODFE bit.

SPICN0.3 (MODF) Mode Fault Flag. This bit is the mode fault flag when the SPI is operating as a master.

When mode fault detection is enabled as MODFE = 1 in master mode, a detection of a

high to low transition on the SSEL pin signifies a mode fault and sets the MODF to 1. This

bit must be cleared to 0 by software once set. Setting this bit to 1 by software causes an

interrupt if enabled. This flag has no meaning in slave mode.

SPICN0.4 (WCOL) Write Collision Flag. This bit indicates a write collision when set to 1. This is caused by

attempting to write to the SPIB while a transfer cycle is in progress. This bit must be cleared

to 0 by software once set. Setting this bit to 1 by software causes an interrupt if enabled.

SPICN0.5 (ROVR) Receive Overrun Flag. This bit indicates a receive overrun when set to 1. This is caused

by two or more characters have been received since the last read by the processor. The

newer data is lost. This bit must be cleared to 0 by software once set. Setting this bit to 1 by

software causes an interrupt if enabled.

SPICN0.6 (SPIC) SPI Transfer Complete Flag. This bit indicates the completion of a transfer cycle when

set to 1. This bit must be cleared to 0 by software once set. Setting this bit to 1 by software

causes an interrupt if enabled.

SPICN0.7 (STBY) SPI Transfer Busy Flag. This bit is used to indicate the current status of the SPI module.

STBY is set to 1 when starting a SPI transfer cycle and is cleared to 0 when the transfer

cycle is completed. This bit is controlled by hardware and is read-only for user software.

SPIB1 (06h, 03h) SPI Data Buffer 1 (16-bit register)

Initialization: This buffer is cleared to 0000h on all forms of reset.

Read/Write Access: Unrestricted read, write is allowed outside of a transfer cycle; when the STBY bit is set, write

is blocked and causes write collision error.

SPIB1.15 to SPIB1.0 SPI Data Buffer 1 Bits 15:0. Data for SPI is read from or written to this location. The serial

transmit and receive buffers are separate but both are addressed at this location.

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