Serial Communications Interface (SCI)
SCI-A Programmable Data Format
Start LSB
2
3
4
5
7
MSB
Parity Stop 1
Addr/
Data
6
This bit present only in Address-bit mode
Stop 2
NRZ (non-return to zero) format
ADDR/IDLE
MODE
STOP
BITS
EVEN/ODD
PARITY
PARITY
ENABLE
LOOP BACK
ENABLE
SCI
CHAR2
SCI
CHAR1
SCI
CHAR0
Communications Control Register (SCICCR) – 0x007050
0 = 1 Stop bit
1 = 2 Stop bits
0 = Odd
1 = Even
0 = Disabled
1 = Enabled
0 = Disabled
1 = Enabled
0 = Idle-line mode
1 = Addr-bit mode
7
6
5
4
3
2
1
0
# of data bits = ( 1)
e.g.
110b
gives 7 data bits
[SCI-B Communications Control Register (SCICCR) – 0x007750]
The basic unit of data is called a
character
and is 1 to 8 bits in length. Each character of data is
formatted with a start bit, 1 or 2 stop bits, an optional parity bit, and an optional address/data bit.
A character of data along with its formatting bits is called a
frame
. Frames are organized into
groups called blocks. If more than two serial ports exist on the SCI bus, a block of data will
usually begin with an address frame which specifies the destination port of the data as determined
by the user’s protocol.
The start bit is a low bit at the beginning of each frame which marks the beginning of a frame.
The SCI uses a NRZ (Non-Return-to-Zero) format which means that in an inactive state the
SCIRX and SCITX lines will be held high. Peripherals are expected to pull the SCIRX and
SCITX lines to a high level when they are not receiving or transmitting on their respective lines.
When configuring the SCICCR, the SCI port should first be held in an inactive state.
This
is done using the SW RESET bit of the SCI Control Register 1 (SCICTL1.5). Writing a 0 to this
bit initializes and holds the SCI state machines and operating flags at their reset condition. The
SCICCR can then be configured. Afterwards, re-enable the SCI port by writing a 1 to the SW
RESET bit. At system reset, the SW RESET bit equals 0.
11 - 12
C28x - Communications
Содержание C28 Series
Страница 64: ...Summary 3 16 C28x Peripheral Registers Header Files ...
Страница 78: ...Interrupt Sources 4 14 C28x Reset and Interrupts ...
Страница 218: ...Lab 9 DSP BIOS 9 22 C28x Using DSP BIOS ...
Страница 244: ...Lab 10 Programming the Flash 10 26 C28x System Design ...
Страница 273: ...Appendix A eZdsp F2812 C28x Appendix A eZdsp F2812 A 1 ...
Страница 275: ...Appendix eZdsp F2812 eZdsp F2812 Connector Header and Pin Diagram C28x Appendix A eZdsp F2812 A 3 ...
Страница 276: ...Appendix P2 Expansion Interface A 4 C28x Appendix A eZdsp F2812 ...
Страница 277: ...Appendix P4 P8 P7 I O Interface C28x Appendix A eZdsp F2812 A 5 ...
Страница 278: ...Appendix A 6 C28x Appendix A eZdsp F2812 ...
Страница 279: ...Appendix P5 P9 Analog Interface C28x Appendix A eZdsp F2812 A 7 ...
Страница 281: ...Appendix JP7 JP8 JP11 JP12 Boot Mode Select JP9 PLL Disable DS1 DS2 LEDs C28x Appendix A eZdsp F2812 A 9 ...
Страница 282: ...Appendix A 10 C28x Appendix A eZdsp F2812 TP1 TP2 Test Points ...