668-0011 Rabbit Semiconductor, 668-0011 Datasheet - Page 155

• Manufacturer Part Number: 668-0011
• Description: IC MPU RABIT3000A 55.5MHZ128LQFP
• Manufacturer: Rabbit Semiconductor

Specifications of 668-0011

• Rohs Status: RoHS non-compliant
• Processor Type: Rabbit 3000 8-Bit
• Speed: 55.5MHz
• Voltage: 2.5V, 2.7V, 3V, 3.3V
• Mounting Type: Surface Mount
• Package / Case: 128-LQFP
• Features: -
• Other names: 316-1043

A sample HDLC interrupt handler is shown below for Serial Port E.
18.3.3 More on Clock Synchronization and Data Encoding
The transmitter is not capable of sending an arbitrary number of bits, but only a multiple
of bytes. However, the receiver can receive frames of any bit length. If the last “byte” in
the frame is not eight bits, the receiver sets a status flag that is buffered along with this last
byte. Software can then use the table below to determine the number of valid data bits in
this last “byte.” Note that the receiver transfers all bits between the opening and closing
flags, except for the inserted zeros, to the receiver data buffer.
Chapter 18 Serial Ports E – F
hdlc_sere_isr::
rx_ready:
check_for_tx:
done:
push af
ioi ld a, (SESR)
bit 7,a
push af
jr
; check status byte in A for abort or invalid CRC flags
ioi ld a, (SEDR)
; store byte in A here
pop af
bit 3,a
jr nz, done
; check status byte in A for transmit finish reason (CRC, abort, etc.)
; get next byte to be transmitted into A here; if it is the last
;
ioi ld (SEDR), a
pop af
ipres
ret
z, check_for_tx
byte of the packet, load it into SEAR or SELR instead
Last Byte Bit Pattern
bbbbbbb0
bbbbbb01
bbbbb011
bbbb0111
bbb01111
bb011111
b0111111
; get status
; check if byte ready in RX buffer
; save status for next check
; read byte and clear interrupt
; check if TX buffer was emptied
; load next byte into buffer and clear interrupt
Valid Data Bits
7
6
5
4
3
2
1
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