收藏本站
4.2.2 Serial Communication Drivers
Library files included with Dynamic C provide a full range of serial communications sup-
port. The RS232.LIB library provides a set of circular-buffer-based serial functions. The
PACKET.LIB library provides packet-based serial functions where packets can be delim-
ited by the 9th bit, by transmission gaps, or with user-defined special characters. Both
libraries provide blocking functions, which do not return until they are finished transmit-
ting or receiving, and nonblocking functions, which must be called repeatedly until they
are finished. For more information, see the Dynamic C Function Reference Manual and
Technical Note 213, Rabbit 2000 Serial Port Software .
4.2.2.1 RS-485 Serial Communication Drivers
The JR485.LIB library in the Dynamic C LIB/JRABLIB directory contains three RS-485
drivers for use with the BL1810. These drivers are used with the drivers for Serial Port D in
the RS232.LIB library because serDopen uses PC0 (TXD) and PC1 (RXD), which are
connected to pin 4 and pin 1 of the SP483EN RS-485 chip at U6. This chip is half duplex,
requiring pin 3 (Data Enable) to be high for pins 6 and 7 to act as outputs, and low for
those pins to act as inputs.
Parallel Ports D and E on the Rabbit 2000 are double-buffered to provide precisely timed
updating of the output pins. Each port is divided into an upper and a lower nibble. All bits
of each nibble must be updated simultaneously. Each nibble may be updated constantly at
a rate of perclk /2 or on a match of a selected timer (Timer A1, B1, or B2).
The bits used to select the update rate for each nibble are left random at power-up. If a mode
other than perclk /2 is selected, the bits of a particular port will not update on a simple
writing to the port’s data register. In particular, PD5, the RS-485 transmitter control, will not
set the RS-485 transmitter enable unless the upper nibble of Port D is configured properly.
The JR485Init function in Dynamic C release 6.16 has provision to disable the special
clocking features associated with the high nibble of Port D. This effectively disables
digital-to-analog (D/A) converter output channel DA1, the low-resolution D/A converter
channel, which also uses PD4. Channel DA0 has its PWM output clocked separately with
the low nibble, and so is not affected. Because the analog-to-digital converter uses D/A
channel DA0, analog-to-digital conversion is not affected.
There are three RS-485 serial drivers.
void Jr485Init();
Sets up parallel port D pins for RS-485 use.
void Jr485Tx();
Sets pin 3 (DE) of the SP483EN chip high to disable Rx and enable Tx.
void Jr485Rx();
Resets pin 3 (DE) of the SP483EN chip low to disable Tx and enable Rx.
38
Rabbit 2000 Development Kit
发布紧急采购，3分钟左右您将得到回复。

采购需求

(若只采购一条型号，填写一行即可)

发布成功！您可以继续发布采购。也可以进入我的后台，查看报价

发布成功！您可以继续发布采购。也可以进入我的后台，查看报价

*型号 *数量 厂商 批号 封装
添加更多采购

我的联系方式

*
*
*
相关PDF资料
101-0523 KIT DEV RABBIT3000/RCM3000
101-1109 KIT EMBEDDED PLC APPLICATION
101-1147 KIT RIO PROGRAM I/O
101-606 CONN SOCKET IDC 60POS W/KEY GOLD
10113616-01531LF CONN MOD JACK 8PORT 8/8 R/A PCB
10117863-5036010LF CONN MOD JACK 8/8 R/A PCB
10118061-5005010LF CONN MOD JACK 2PORT 8/8 R/A PCB
10118062-5001310LF CONN MOD JACK 4PORT 8/8 R/A PCB
相关代理商/技术参数
101-0359-000 制造商:ITT Interconnect Solutions 功能描述:1010359000 / 101-0359-000 / Circular
10103592 制造商:FCI-CONNECTOR 制造商全称:FCI connector 功能描述:MICRO-USB B-TYPE REVERSE
10103592-0001LF 功能描述:USB接头 5P Quick Connect Micro USB TypeB Plug RoHS:否 制造商:FCI 产品:USB Type A Connectors 标准:USB 3.0 端口数量: 位置/触点数量:9 型式:Female 电流额定值:1.8 A 安装风格:Through Hole 端接类型:Solder Pin 连接器类型:USB 3.0 Receptacle
10103593 制造商:FCI-CONNECTOR 制造商全称:FCI connector 功能描述:MICRO-USB B-TYPE MID-MOUNT
10103593-0001LF 功能描述:USB接头 5P Quick Connect Micro USB TypeB RCPT RoHS:否 制造商:FCI 产品:USB Type A Connectors 标准:USB 3.0 端口数量: 位置/触点数量:9 型式:Female 电流额定值:1.8 A 安装风格:Through Hole 端接类型:Solder Pin 连接器类型:USB 3.0 Receptacle
10103593-0001LF 制造商:FCI 功能描述:MICRO USB B, RECEPTACLE, 5POS, SMT RT AN
10103594 制造商:FCI-CONNECTOR 制造商全称:FCI connector 功能描述:MICRO-USB B-TYPE RECEP.
10103594-0001LF 功能描述:USB接头 5P Quick Connect Micro USB TypeB Rcpt RoHS:否 制造商:FCI 产品:USB Type A Connectors 标准:USB 3.0 端口数量: 位置/触点数量:9 型式:Female 电流额定值:1.8 A 安装风格:Through Hole 端接类型:Solder Pin 连接器类型:USB 3.0 Receptacle