AN2502 Freescale Semiconductor / Motorola, AN2502 Datasheet - Page 3

• Manufacturer Part Number: AN2502
• Description: Using Two Channels of the HC08 TIM to Achieve a Full-Duplex Software SCI
• Manufacturer: Freescale Semiconductor / Motorola

Enhanced Mode
Normal Mode
Registers
MOTOROLA
NOTE:
Using Two Channels of the HC08 TIM to Achieve a Full-Duplex Software SCI
Features of enhanced mode:
In normal mode, five RAM variables are declared: one for status flags and four
for data (receiving and transmitting).
All registers that have an “r” before the register name are pseudo registers that
have been created in RAM. Therefore, these registers do not appear in the
device data sheet. The rSCSR register in
register. All other registers are normal physical registers as described in the
device data sheet.
Read:
Write:
•
•
•
•
•
•
•
•
RPF — Reception in Progress Flag
TPF — Transmit in Progress Flag
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1 = Reception is in progress
0 = Reception is not in progress
1 = Transmission is in progress
0 = Transmission not in progress
Full-duplex operation
Minimal software overhead
Easily configured for different baud rates
Interrupt request by each reception bit
Two different subroutines available for receiver full and for transmitter
empty, each with an enable/disable bit
Three flags for error detection:
–
–
–
12 easily configured data frame formats:
–
–
–
Two enable/disable bits for reception and/or transmission
Bit 7
RPF
ORE — Overrun error
FE — Framing error
PE — Parity error
Eight or nine data bits
Even parity, odd parity, or no parity bit
One or two stop bits
Figure 2. SCI Status Register (rSCSR)
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= Unimplemented or Reserved
TPF
6
SCRF
5
SCTE
4
Figure 2
3
is an example of a pseudo
2
1
AN2502/D
Bit 0
Modes
3