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ELM329P 参数 Datasheet PDF下载

ELM329P图片预览
型号: ELM329P
PDF下载: 下载PDF文件 查看货源
内容描述: CAN解释 [CAN Interpreter]
分类和应用:
文件页数/大小: 76 页 / 353 K
品牌: ELM [ ELM ELECTRONICS ]
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ELM329  
CAN (Single Wire) Transceiver Modes  
The ELM329 was designed with two wire CAN  
(OBDII) applications in mind, but there is no reason  
that it can not be used for single wire CAN applications  
(SAE J2411, etc.), as well. The data format remains  
much the same on the CAN networks - it is really the  
physical interface that differs.  
Single wire CAN transceiver chips are available  
and should be used when connecting the ELM329 to  
single wire CAN networks. These ICs usually provide  
mode inputs which are used to change the state of the  
device - to put it into low power sleep mode, set the  
output to high voltage (12V) mode, etc. The table  
below shows the four modes typically supported by  
single wire CAN transceiver ICs, and the mode inputs  
most often used for each.  
The ELM329 provides two output pins (M0 and  
M1) that may be used to set the modes for a single  
wire CAN transceiver. After every reset or AT D  
command, the level at pins 21 and 22 will be set  
according to PP 20. Note that firmware v1.0 set these  
pins to a low level (mode = sleep) when the IC went to  
low power mode, but the ELM329 no longer changes  
the setting while in low power mode.  
The M0 and M1 pin levels are controlled with the  
Transceiver Mode commands. For example, if you  
wish to put the transceiver into the high voltage  
wakeup mode, simply send;  
>AT TM 2  
OK  
and to restore the mode to normal, send:  
TM  
#
M1  
M0  
>AT TM 3  
OK  
Mode  
(pin 21) (pin 22)  
0
1
2
3
0
0
1
1
0
1
0
1
Sleep  
If you do not require these pins for a single wire  
CAN application, they may be used as general  
purpose outputs., much like the Control output.  
High Speed  
High Voltage Wakeup  
Normal  
Control Module Operation  
The ELM329 provides two general purpose inputs  
and one general purpose output that you may use for  
your own control applications.  
The two inputs are provided for monitoring signals  
that you connect. They both have Schmitt trigger  
wave-shaping on the input so can accommodate even  
the slowest moving signals. These inputs should also  
be protected from voltages which exceed the supply  
limits (usually a series resistance is all that is need for  
this).  
The Control output (pin 4) may be set to a high or  
low level at any time with the AT C command. After a  
power on reset, the Control output is always reset to a  
low level.  
To set the Control output high, simply send:  
>AT C1  
and to set it low, send:  
>AT C0  
Reading the level at an input is simply a matter of  
sending the appropriate AT command. For pin 12,  
send:  
Note that the Control output can also be selected  
to show the internal CAN activity signal (as determined  
by the CAN Monitor at pin 11). Simply set PP 0F bit 0  
to ‘1’ in order to enable it.  
There are no restrictions on how you use these  
inputs and the output. You may wish to control a  
buzzer, perhaps an LED, or to monitor a switch input,  
or voltage level - it’s up to you.  
>AT IN1  
0
and the ELM329 reports the logic level at the input (‘0’  
in this case). Similarly, the level at pin 13 is read with:  
>AT IN2  
1
ELM329DSB  
Elm Electronics – Circuits for the Hobbyist  
www.elmelectronics.com  
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