Table 12-12. Status Register Clocked Serial (Ports A-D only)

 

Serial Port x Status Register

(SASR)

(Address = 0xC3)

 

 

 

 

(SBSR)

(Address = 0xD3)

 

 

 

 

(SCSR)

(Address = 0xE3)

 

 

 

 

(SDSR)

(Address = 0xF3)

Bit(s)

 

Value

Description (Clocked serial mode only)

 

 

 

 

 

 

 

0

The receive data register is empty

 

7

 

 

 

 

 

 

1

There is a byte in the receive buffer. The serial port will request an interrupt

 

 

 

 

while this bit is set. The interrupt is cleared when the receive buffer is empty.

 

 

 

 

 

 

 

 

6

 

0

This bit is always zero in clocked serial mode.

 

 

 

 

 

 

5

 

0

The receive buffer was not overrun.

 

 

 

 

 

 

 

1

The receive buffer was overrun. This bit is cleared by reading the receive buffer.

 

 

 

 

 

 

 

4

 

0

This bit is always zero in clocked serial mode.

 

 

 

 

 

 

 

 

 

0

The transmit buffer is empty.

 

 

 

 

 

 

3

 

 

The transmit buffer is not empty. The serial port will request an interrupt when

 

1

the transmitter takes a byte from the transmit buffer. Transmit interrupts are

 

 

 

 

cleared when the transmit buffer is written, or any value (which will be ignored)

 

 

 

 

 

 

is written to this register.

 

 

 

 

 

 

 

 

 

 

0

The transmitter is idle.

 

 

 

 

 

 

2

 

1

The transmitter is sending a byte. An interrupt is generated when the transmitter

 

 

clears this bit, which occurs only if the transmitter is ready to start sending

 

 

 

another byte but the transmit buffer is empty.

 

 

 

 

 

 

1:0

 

00

These bits are always zero in clocked serial mode.

 

 

 

 

 

 

 

User’s Manual

171

Page 180
Image 180
Jameco Electronics 3000 Status Register Clocked Serial Ports A-D only, Bits Value Description Clocked serial mode only