Abov A96G174 - Receiver Time out (RTO); Figure 77. Example for RTO in USART; Table 24. Example Condition of RTO

14. USART A96G174/A96S174 User’s manual
142
14.10 Receiver time out (RTO)
This USART system supports the time out function. This function generates an interrupt when stop bits
are not in RX line during URTOC setting value. RTO Count stops in RXD signal live state and RTO
Clear/Start is executed by stop bit recognition.
Example condition is listed in Table 24.
Table 24. Example Condition of RTO
Condition
 sysclk = 16MHz
 Baud rate = 115,200 bps
 Asynchronous Normal Mode (U2X = 0)
Baud rate
sysclk / 16 x (UBAUD + 1)
Calculated UBAUD
 (1000000 / Target Baud rate) – 1 = 7.68
 Error rate = 0.68
➔
➔
➔
UBAUD = 8
Real baud rate at
sysclk 16Mhz
111,111 bps
1 bit time
9us
Maximum count time
9us * 65536(16bit count) = 589.8ms
USART RX
Start bit Data bit Parity bit Stop bit
1 bit time
= 9us (@111111 bps)
1 Frame time (parity, 1 Stop)
= 99us (@111111 bps)
A96G174
USART RX
Data 0x00
Case1
RTO count stops in RXD signal Live state.
Even if it is set smaller than frame time, it does not count..
RTO Clear&Start is executed by stop bit
A96G174
USART RX
Frame Error
Case2
If a disconnect problem occurs, interrupt is
Generated after the internal buffer 2 data is
filled.
Frame error can be checked by Frame
Error State Flag.
Figure 77. Example for RTO in USART