pic - How to detect that an i2c slave doesn't respond to the master on PIC18f -

-

i have pic18f i2c master , other devices slaves.

i want detect if slave not on bus or if doesn't responds.

right now, communication master<->slaves works except when slave doesn't responds. when happens, pic stays in waiting state , whole program stopped.

how can detect , fix ? (in software way)

for information, i'm working on pic18f25k22.

i assume using mplab c18. source i2c functions can found in: c:\program files (x86)\microchip\mplabc18\v3.46\src\pmc_common\i2c

next, you'll need figure out functions hanging , write own versions don't go endless loops if slave doesn't respond. readi2c hanging waiting slave respond. replace myreadi2c takes timeout parameter. modified version of code in i2c_read.c.

#if defined (i2c_v1) int myreadi2c( long timeout ) { if( ((sspcon1&0x0f)==0x08) || ((sspcon1&0x0f)==0x0b) )  //master mode   sspcon2bits.rcen = 1;           // enable master 1 byte reception   while ( !sspstatbits.bf && timeout > 0) timeout--;      // wait until byte received     return timeout == 0 ? (-1) : ( sspbuf );              // return read byte  } #endif  #if defined (i2c_v4) int myreadi2c( long timeout) {   while ( !sspstatbits.bf && timeout > 0) timeout--;      // wait until byte received     return timeout == 0 ? (-1) : ( sspbuf );              // return read byte  } #endif

myreadi2c return -1 on timeout , unsigned char value (0 - 255) on success. need modify other i2c functions use in similar way avoid loops test register status values. value timeout, need find value through experimentation depending on devices clock speed , peripherals response time.


Comments

Post a Comment

Popular posts from this blog

java - Jmockit String final length method mocking Issue -

-
using jmockit 1.2 jar, trying mock string's length method getting unexpected invocation exception: failed: test java.lang.illegalstateexception: missing invocation mocked type @ point; please make sure such invocations appear after declaration of suitable mock field or parameter @ stringdemo.testa$1.<init>(testa.java:17) @ stringdemo.testa.test(testa.java:13) i using testng: @test public void test() throws exception { new expectations() { @mocked("length") string astring; { astring.length(); result = 2; } }; system.out.println(a.showa("test")); } } actual class a: public class { public static int showa(string str){ int a= str.length(); return a; } } this wrong way of recording expected results. shouldn't mock , record string's length() method, record showa() instead. here solution @suppresswarnings("unused...
Read more

What is the difference between data design and data model(ERD) -

-
i have google question , find answer in day. know, data design many many table have list column,and mark pk , fk. why er-diagram have find this? data design process of designing database. main output of data design detailed logical data model of database. some people data design includes of needed logical , physical design choices , physical storage parameters needed generate design in data definition language. technically, database analysis, database analysts (dbas) trained do. while person can both data design , database analysis, these 2 different tasks. data design models data. database analysis takes model , applies 1 or more database engines (relational, hierarchical, nosql). a logical data model 1 of main outputs of data design. data model represented entity relationship diagram, or er diagram.
Read more

ios - Can NSManagedObject conform to NSCoding -

-
i need transfer single object across device. right converting nsmanagedobject dictionary , archiving , sending nsdata. upon receiving unarchiving it. transfer nsmanagedobject archiving , unarchiving instead of creating intermediate data object. @interface test : nsmanagedobject<nscoding> @property (nonatomic, retain) nsstring * title; @end @implementation test @dynamic title; - (id)initwithcoder:(nscoder *)coder { self = [super init]; if (self) { self.title = [coder decodeobjectforkey:@"title"]; //<crash } return self; } - (void)encodewithcoder:(nscoder *)coder { [coder encodeobject:self.title forkey:@"title"]; } @end nsdata *archivedobjects = [nskeyedarchiver archiveddatawithrootobject:testobj]; nsdata *objectsdata = archivedobjects; if ([objectsdata length] > 0) { nsarray *objects = [nskeyedunarchiver unarchiveobjectwithdata:objectsdata]; } the problem above code is. crashes @ self.title in initwithcoder sa...
Read more