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temtronic
Joined: 01 Jul 2010
Posts: 9229
Location: Greensville,Ontario
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 Posted: Tue Feb 19, 2019 9:47 am |
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While I don't use DSPICs...
I was curious as 'tolerant' doesn't necessarily mean 'it will work', so I downloaded the datasheet as well as DS70330 (ref app note). I can't see anywhere that MicroChip says you can tie the bus to +5 while using a VDD of 3v3.
It'd be nice to have someone confirm this is allowed. |
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Baskar Veerappan
Joined: 17 Feb 2019
Posts: 9
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| Posted: Tue Feb 19, 2019 10:32 am |
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Dear temtronic,
I am able to Write to slaves without any issues out only reading causes issues
creating a Bus Collision.
_________________
Regards
Baskar V |
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Baskar Veerappan
Joined: 17 Feb 2019
Posts: 9
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| Code |
| Posted: Tue Feb 19, 2019 10:35 am |
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This is my code
Please Correct if anything is wrong
| Code: |
#define CLK_16MHZ
#define FCY 16010000 /*16.01 MHz*/
#ifndef CLK_16MHZ
#define FCY 69400000 /*69.4 MHz*/
#define CLK_138MHZ
#endif
#define MAXTASK (5u)
#define DS3231_RD ((104u << 1u)|1u) /* RW Bit 1 */
#define DS3231_WR (104u << 1u) /* RW Bit 0 */
typedef enum { TASK0=0u,TASK1,TASK2,TASK3,TASK4} T_NO ;
typedef enum
{
T_RUN, /* Run the Task */
T_SUSPEND, /* Wait For the event to Occur */
T_STOP, /* Stop the task. Enabled by user */
T_WAIT /* Wait For specific Period */
}T_STATE ;
typedef struct
{
T_NO TaskNo;
T_STATE TaskState;
Uint16 WaitTime ;
void (*Task)(void);
}SCHEDULER ;
typedef struct
{
SCHEDULER *OsPtr ;
T_NO CurrentTask ;
}MAINTASK;
/********************************************************************************
* FUNCTION : I2C MASTER INITILIZATION
* ARGUMENT1 : NONE
* RETURN TYPE : NONE
* NOTE : MASTER MODE
* : I2C BAUD RATE FORMULA : I2C1BRG = {[((1/FScl)-Delay)*Fcy]-2}
* : DELAY VARIES FROM 110nS to 130nS
* REFERENCE : MICROCHIP REFERENCE MANUAL : DS70330
********************************************************************************/
static void dsPIC33EP512GP502_I2C2MasterInit(void)
{
TRISB = (BIT5|BIT6); /* Inputs for I2C2 */
I2C2CON = CLEAR ; /*I2C2 Disabled */
#ifndef CLK_16MHZ /*Device Enters Full speed 70MIPS Approx */
I2C2BRG = I2C_CLK_400KHz_AT_138MHz;
#endif
#ifdef CLK_16MHZ /*Device Enters Low speed 16MIPS Approx */
I2C2BRG = I2C_CLK_100KHz_AT_16MHz;
#endif
I2C1ADD = CLEAR ;
I2C1MSK = CLEAR ;
I2C2CON = (BIT15|BIT13|BIT12|BIT8);
}
/********************************************************************************
* FUNCTION : SET I2C2 TIME OUT TIME
* ARGUMENT1 : NONE
* RETURN TYPE : NONE
* NOTE : -/-
********************************************************************************/
void inline SetTimeoutTime(void)
{
#ifndef CLK_16MHZ /*Default Clock is 138 MHz*/
I2C2.TimeOut = 80000;/*Approx 2mS 70MIPS 0.001/Instrction Cycle14.4nS*/
#endif
#ifdef CLK_16MHZ /* Debug Clock is 16 MHz*/
I2C2.TimeOut = 17010;/*Approx 2mS 16MIPS 0.001/Instrction Cycle62.4nS*/
#endif
}
/********************************************************************************
* FUNCTION : BUS IDLE I2C2
* ARGUMENT1 : NONE
* RETURN TYPE : BUS IDLE [1] NOT IDLE [0]
* NOTE : -/-
********************************************************************************/
Flag BusIdle_I2C2(void)
{
Flag ReturN = 0 ;
ReturN = (((I2C2STAT & (BIT14|BIT10|BIT7|BIT6)) == 0u) &&
(( I2C2CON & (BIT2|BIT1|BIT0)) == 0u)) ;
return ReturN ;
}
/********************************************************************************
* FUNCTION : GENERATE ACK ON I2C2
* ARGUMENT1 : ACK TYPE [0-ACK, 1-NACK]
* RETURN TYPE : NONE
* NOTE : -/-
********************************************************************************/
void PutAcknowledgeI2C2(Flag AckBit)
{
I2C2CONbits.ACKDT = AckBit ;
I2C2CONbits.ACKEN = TRUE ;
}
/********************************************************************************
* FUNCTION : READ ACK FROM SLAVE ON I2C2 BUS
* ARGUMENT1 : NONE
* RETURN TYPE : ACK TYPE [0-ACK, 1-NACK,2 ACK TIMEOUT ERROR]
* NOTE : -/-
********************************************************************************/
Uint08 GetAcknowledgeI2C2(void)
{
if(I2C2.Sts == I2C_OK) {
SetTimeoutTime();
while(I2C2.TimeOut != 0u) {
if((BusIdle_I2C2() == TRUE) && (!I2C2STATbits.TBF)) {
I2C2.Sts = I2C_OK ;
return (I2C1STATbits.ACKSTAT);
} else { I2C2.TimeOut -- ; }
}
return(I2C2.Sts=ACK_ERR) ;
}
else { return(I2C2.Sts=ACK_ERR);}
}
/********************************************************************************
* FUNCTION : INITIATE START,RESTART,STOP CONDITION ON I2C2 BUS
* ARGUMENT1 : START,RESTART,STOP
* RETURN TYPE : NONE
* NOTE : -/-
********************************************************************************/
void dsPIC33EP512GP502_IIC2(STATE_IIC Action)
{
if(I2C2.Sts != I2C_OK) {
dsPIC33EP512GP502_I2C2MasterInit();
} else { /* No Operation */ }
SetTimeoutTime();
while(I2C2.TimeOut != 0u) {
I2C2.Sts = I2C_OK ;
((BusIdle_I2C2() == TRUE) ? ((Action == START) ? (I2C2CONbits.SEN = TRUE) :
((Action == RESTART) ? (I2C2CONbits.RSEN = TRUE):(I2C2CONbits.PEN = TRUE))):
(I2C2.Sts = BUS_NOT_IDLE) ) ;
(I2C2.Sts != BUS_NOT_IDLE) ? (I2C2.TimeOut = CLEAR) : (I2C2.TimeOut--) ;
}
}
/********************************************************************************
* FUNCTION : WRITE TO I2C2 BUS
* ARGUMENT1 : NONE
* RETURN TYPE : NONE
* NOTE : -/-
********************************************************************************/
void IIC2_Transmit(Uint08 DaTa)
{
if(I2C2.Sts == I2C_OK) {
SetTimeoutTime();
while(I2C2.TimeOut != 0u) {
if(BusIdle_I2C2() == TRUE) {
I2C2TRN = DaTa ; /*Shift Out*/
I2C2.Sts = I2C_OK ;
return ;
}
else { I2C2.TimeOut -- ; }
}
I2C2.Sts = I2C_ERR;
return ;
}
else { /* Exit Without Operation */}
}
/********************************************************************************
* FUNCTION : READ FROM I2C2 BUS
* ARGUMENT1 : NONE
* RETURN TYPE : READ DATA
* NOTE : -/-
********************************************************************************/
Uint08 IIC2_Recieve(void)
{
Uint08 RxData = NULL ;
if(I2C2.Sts == I2C_OK) {
SetTimeoutTime();
while(I2C2.TimeOut != 0u) {
if(I2C2STATbits.RBF == TRUE) {
RxData = I2C2RCV; /*Shift In */
I2C2.Sts = I2C_OK ;
return RxData ;
}
else { I2C2.TimeOut -- ; }
}
I2C2.Sts = I2C_ERR;
return NULL ;
}
else { return NULL ; /* Exit Without Operation */}
}
/********************************************************************************
* FUNCTION : READ TIME FROM DS3231 RTC CHIP
* ARGUMENT1 : ADDRESS OF INTERNAL REGISTER TO BE READ
* RETURN TYPE : RTC READ VALUE
* NOTE : -/-
********************************************************************************/
Uint08 Read_DS3231(Uint08 Adrs )
{
Uint08 RxD =0; Flag AckNow=1;
AckNow = I2C2STATbits.ACKSTAT ;
I2C2CONbits.RCEN = TRUE ;
dsPIC33EP512GP502_IIC2(START);
IIC2_Transmit(DS3231_WR);
IIC2_Transmit(Adrs); /*Internal Register Address */
AckNow = (GetAcknowledgeI2C2() == ACK);
dsPIC33EP512GP502_IIC2(RESTART);
IIC2_Transmit(DS3231_RD);/* Bus Collision Occurs Here Making SDA 0 for Ever*/
RxD = IIC2_Recieve();
PutAcknowledgeI2C2(NACK);
dsPIC33EP512GP502_IIC2(STOP);
return RxD ;
}
/********************************************************************************
* FUNCTION : SERIAL COMMUNICATIONS INIT
* ARGUMENT1 : NONE
* RETURN TYPE : NONE
* NOTE : ALL TIMER SETTINGS
********************************************************************************/
static inline void dsPIC33EP512GP502_SerialCoM(void)
{
dsPIC33EP512GP502_I2C2MasterInit();
dsPIC33EP512GP502_UARTMaster();
}
/********************************************************************************
* FUNCTION : HARDWARE INITILIZATION
* ARGUMENT1 : NONE
* RETURN TYPE : NONE
* NOTE : NONE
********************************************************************************/
void dsPIC33EP512GP502_Hw_Initialization(void)
{
dsPIC33EP512GP502_OscConfig(); /* Oscillator Configurations */
dsPIC33EP512GP502_PMD(); /* PMD Configurations */
dsPIC33EP512GP502_IO_Setting(); /* IO Pin Configurations */
dsPIC33EP512GP502_Interrupts(); /* Interrupt Settings */
dsPIC33EP512GP502_Timers(); /* Timer Settings */
dsPIC33EP512GP502_SerialCoM(); /* Serial Communications */
dsPIC33EP512GP502_RemapingIO(); /* PPS- Remaping IO */
}
/********************************************************************************
* FUNCTION : TASK STATE CONTROL
* ARGUMENT1 : TASK NUMBER
* ARGUMENT2 : WAIT TIME [IF TASK STATE IS SET TO WAIT ELSE PASS 0]
* RETURN TYPE : NONE
* CATEGORY : TASK MANAGEMENT
********************************************************************************/
void SetTaskState(T_NO TaskNo ,T_STATE StatE,Uint16 Time)
{
Main.OsPtr[TaskNo].TaskState = StatE ;
Main.OsPtr[TaskNo].WaitTime = Time ;
}
/********************************************************************************
* FUNCTION : TASK_INITIALIZATION TASK
* ARGUMENT1 : NONE
* RETURN TYPE : NONE
********************************************************************************/
void Task_Initialization(void)
{
dsPIC33EP512GP502_Hw_Initialization();
dsPIC33EP512GP502_Sw_Initialization(); /*Variables Initialization */
Init_LCD_4bit();
Print_LCD("Welcome Boss...",STRING,Line2); // Test Purpose
Display_Auto_clear(2000,Line2+3,8); // Test Purpose Clear after 2 Seconds
SetTaskState(TASK0,T_STOP,NULL); // No More Further Execution
}
/********************************************************************************
* FUNCTION : 500mS TASK
* ARGUMENT1 : NONE
* RETURN TYPE : NONE
********************************************************************************/
void Task_500mS(void)
{
Uint16 Sec=0;
Sec = Read_DS3231(0); // Read Seconds Register
Print_LCD(&Sec,INTEGER2,Line3);
SetTaskState(TASK1,T_WAIT,250u); /*250*2mS = 500mS*/
}
/********************************************************************************
* FUNCTION : MAIN
* ARGUMENT1 : NOT REQUIRED
* RETURN TYPE : NONE
********************************************************************************/
int main(void)
{
Uint08 TskNow ;
SCHEDULER TaskHandler[MAXTASK] = {
{ TASK0 , T_RUN , 0u , Task_Initialization },
{ TASK1 , T_RUN , 0u , Task_500mS },
{ TASK2 , T_RUN , 0u , Task_1000mS },
{ TASK3 , T_WAIT , 500u, Task_DisplayHandler }, /* 1S Wait*/
{ TASK4 , T_STOP , 0u , Task_AlarmHandler }
} ;
/* Enabling for Global Access */
Main.OsPtr = TaskHandler ;
/* Run Time Task Handling */
for(TskNow = 0; TskNow < MAXTASK; TskNow = ((TskNow+1u)%MAXTASK))
{
if(TaskHandler[TskNow].TaskState == T_RUN) {
Main.CurrentTask = TaskHandler[TskNow].TaskNo;
TaskHandler[TskNow].Task() ;
}
}
return 0 ;
}
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_________________
Regards
Baskar V |
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gaugeguy
Joined: 05 Apr 2011
Posts: 303
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| Posted: Tue Feb 19, 2019 10:44 am |
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5V tolerant pins on PIC24 & PIC33 have the specs in the specific data sheet for that processor under electrical characteristics. This is typical of many:
Voltage on any general purpose digital or analog pin (not 5.5V tolerant) with respect to VSS: -0.3V to (VDD + 0.3V)
Voltage on any general purpose digital or analog pin (5.5V tolerant, including MCLR) with respect to VSS:
When VDD = 0V: -0.3V to +4.0V
When VDD > = 2.0V:. -0.3V to +6.0V
So I2C can be operated this way with 5V tolerant pins. |
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Baskar Veerappan
Joined: 17 Feb 2019
Posts: 9
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| Posted: Tue Feb 19, 2019 10:51 am |
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Anybody Having Working I2C Code for dsPIC33EP512GP502
It will be very helpful if any one provide.
_________________
Regards
Baskar V |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Tue Feb 19, 2019 10:54 am |
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Your posted code is for a Microchip compiler, not CCS.
This is the CCS forum. |
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Baskar Veerappan
Joined: 17 Feb 2019
Posts: 9
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| Posted: Tue Feb 19, 2019 10:59 am |
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Dear PCM Programmer,
Yup you are Right
But I have not used any inbuilt library code from XC16 compiler.
_________________
Regards
Baskar V |
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allenhuffman
Joined: 17 Jun 2019
Posts: 552
Location: Des Moines, Iowa, USA
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| Posted: Wed Apr 26, 2023 10:38 am |
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| daveh wrote: | So apparently when the hardware I2C module is enabled "input(i2c2_SDA)" will always read '0'. [Someone please correct me if I'm wrong]
So instead I'm using the following code which disables the hardware I2C before testing the pin:
| Code: | #bit I2C2EN_BIT = 0x0216.15 // I2CEN bit to enable/disable hardware I2C module
#define i2c2_SDA PIN_B5
I2C2EN_BIT=0; // disable I2C2 Hardware Module
if(!input(i2c2_SDA)){ // SDA stuck low - Fault Condition
output_drive(i2c2_SCL); // set SCL as output
while(!input(i2c2_SDA)){ // Toggle clock line till fault clears
output_toggle(i2c2_SCL);
delay_us(1);
}
output_float(i2c2_SCL); // set SCL as input
}
I2C2EN_BIT=1; // enable I2C2 Hardware Module
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Thanks for posting this, back then.
I just implemented a variation of this one several of our PIC24 boards today. I ran in to an issue where, after Build & Run from the CCS IDE, the board would start up and the I2C bus would be locked. It took a power cycle to get it working. I went searching to see about trying an I2C Bus Reset and found a reference to this post in another thread.
I left out the check for SDA, and just used i2c_init() to start/stop it, so mine was more like this:
| Code: |
// I2C configuration
#define I2C1_CLOCK PIN_B8 // I2C1 clock
#define I2C1_DATA PIN_B9 // I2C1 data
#define I2C_INTERNAL_BUS_SCL I2C1_CLOCK
#define I2C_INTERNAL_BUS_SDA I2C1_DATA
#use i2c (MASTER, FAST=400000, I2C1, stream=INTERNAL_BUS)
...
i2c_init (INTERNAL_BUS, 0); // disable
output_drive(I2C_INTERNAL_BUS_SCL); // set SCL as output
for (int idx=0; idx<20; idx++)
{
output_toggle(I2C_INTERNAL_BUS_SCL); // send clock pulses
delay_us(1);
}
output_float(I2C_INTERNAL_BUS_SCL); // set SCL as input
i2c_init (INTERNAL_BUS); // enable
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_________________
Allen C. Huffman, Sub-Etha Software (est. 1990) http://www.subethasoftware.com
Embedded C, Arduino, MSP430, ESP8266/32, BASIC Stamp and PIC24 programmer.
http://www.whywouldyouwanttodothat.com ? |
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Ttelmah
Joined: 11 Mar 2010
Posts: 19520
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| Posted: Thu Apr 27, 2023 2:06 am |
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If you use the NOINIT setting in the #USE I2C, then the bus is not
started at boot, so you can test the SDA pin and clock before starting the
bus:
| Code: |
#use i2c(I2C1, MASTER, FAST=320000, stream=I2CBUS, NOINIT)
//NOINIT to allow I2C bus hang to be cleared
//I2C startup code
while (input(SDA)==0)
{
//SDA is low. Bus may be hung
//So need to try clocking SCL to release bus
//SDA must be floated during this to avoid an ACK if
//the bus releases
output_float(SDA);
for (temp8=0;temp8<9;temp8++)
{
output_low(SCL);
delay_us(5);
output_float(SCL);
delay_us(5);
} //9*100KHz clocks
output_low(SDA);
delay_us(10);
output_float(SDA);
//This technically generates a STOP.
}
i2c_init(I2CBUS,1); //Now physically initialise bus
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This is how I init I2C. This is the defined sequence in the I2C spec to
release a hung bus. |
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allenhuffman
Joined: 17 Jun 2019
Posts: 552
Location: Des Moines, Iowa, USA
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| Posted: Thu Apr 27, 2023 5:45 pm |
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| Ttelmah wrote: | If you use the NOINIT setting in the #USE I2C, then the bus is not
started at boot, so you can test the SDA pin and clock before starting the
bus:
| Code: |
...
output_low(SCL);
delay_us(5);
output_float(SCL);
delay_us(5);
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Thanks -- useful. Why using float/low versus high/low?
_________________
Allen C. Huffman, Sub-Etha Software (est. 1990) http://www.subethasoftware.com
Embedded C, Arduino, MSP430, ESP8266/32, BASIC Stamp and PIC24 programmer.
http://www.whywouldyouwanttodothat.com ? |
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newguy
Joined: 24 Jun 2004
Posts: 1908
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| Posted: Thu Apr 27, 2023 8:13 pm |
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| allenhuffman wrote: | | Thanks -- useful. Why using float/low versus high/low? |
He's just exactly mimicking what the peripheral does: actively pull the line low, then release - not drive high. That's what the pullups are there for. |
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Ttelmah
Joined: 11 Mar 2010
Posts: 19520
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| Posted: Fri Apr 28, 2023 12:44 am |
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and remember that the whole point of I2C, is that it supports multiple
devices potentially pulling the lines 'low' at the same time, and can do this
because none ever _drive_ the lines high. If you drive a line high it only
takes another device to be pulling the line low, and you have potentially
damaging currents flowing... 
I2C relies on having historically 'open collector; drives. Low only. Drive
upwards is just the pull-up resistor, or an accelerator (which actively pulls
up, but only once the voltage is already rising). |
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