SC1100 Datasheet, PDF (331/348 Pages) National Semiconductor (TI) – Geode™ Information Appliance On a Chip

Electrical Specifications (Continued)
7.3.8 Serial Port (UART)
Table 7-24. UART, Sharp-IR, SIR, and Consumer Remote Control Parameters
Symbol Parameter
Min
Max
Unit Comments
t_BT
t_CMW
t_CMP
t_SPW
S_DRT
t_SJT
Single Bit Time in UART and
Sharp-IR
Modulation Signal Pulse
Width in Sharp-IR and
Consumer Remote
Control
Modulation Signal Period in
Sharp-IR and Consumer
Remote Control
SIR Signal Pulse Width
SIR Data Rate Tolerance
% of Nominal Data Rate
t_BTN - 25 ¹
t_BTN - 2%
t_CWN - 25 ²
500
t_CPN - 25 ³
t_MMIN ⁴
(³/₁₆) x t_BTN - 15 ¹
1.48
1
SIR Leading Edge Jitter
% of Nominal Bit Duration
t_BTN + 25
t_BTN + 2%
t_CWN + 25
t_CPN + 25
t_MMAX ⁴
(³/₁₆) x t_BTN + 15 ¹
1.78
± 0.87%
± 2.0%
± 2.5%
± 6.5%
ns Transmitter
ns Receiver
ns Transmitter
ns Receiver
ns Transmitter
ns Receiver
ns Transmitter, Variable
µs Transmitter, Fixed
µs Receiver
Transmitter
Receiver
Transmitter
Receiver
1. t_BTN is the nominal bit time in UART, Sharp-IR, SIR and Consumer Remote Control modes. It is determined by the set-
ting of the Baud Generator Divisor registers.
2. t_CWN is the nominal pulse width of the modulation signal for Sharp-IR and Consumer Remote Control modes. It is de-
termined by the MCPW field (bits [7:5]) of the IRTXMC register and the TXHSC bit (bit 2) of the RCCFG register.
3. t_CPN is the nominal period of the modulation signal for Sharp-IR and Consumer Remote Control modes. It is determined
by the MCFR field (bits [4:0]) of the IRTXMC register and the TXHSC bit (bit 2) of the RCCFG register.
4. t_MMIN and t_MMAX define the time range within which the period of the incoming subcarrier signal has to fall in order for
the signal to be accepted by the receiver. These time values are determined by the contents of register IRRXDC and
the setting of the RXHSC bit (bit 5) of the RCCFG register.
UART
Sharp IR
Consumer
Remote
Control
t_CMW
t_SPW
SIR
t_BT
t_CMP
Figure 7-39. UART, Sharp-IR, SIR, and Consumer Remote Control Timing
Revision 1.1
331
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