I2C Communication between PIC18F4550 and AS5600

Hello,
I am trying to communicate between PIC and AS5600 chip. I am not sure if the commands I send are correct. The only data I receive back from AS5600 is "6" for B0 and "6" for B1.

Here is part of my code:

define LOADER_USED 1
define OSC 24
DEFINE HSER_RCSTA 90h
DEFINE HSER_TXSTA 20h
DEFINE HSER_BAUD 38400
DEFINE HSER_CLROERR 1
Define LCD_DREG PORTD
Define LCD_DBIT 4
Define LCD_RSREG PORTD
Define LCD_RSBIT 1
Define LCD_EREG PORTD
Define LCD_EBIT 0
define LCD_BITS 4
define LCD_LINES 2
define CCP2_REG PORTC
define CCP2_BIT 1
ADCON1 = 15 'make all inputs and outputs digital


TRISA = %11111111 'set up port A as input
TRISC = %10000000 'set up port C as output/input (Rx-1,Tx-0)
TRISB = %11111111 'set up port B as input
TRISD = %00000000 'set up port D as output
TRISE = %00000000 'set up port E as output


PORTC = %01000100
DEFINE I2C_SCL PORTB,1
DEFINE I2C_SDA PORTB,0
DEFINE I2C_SLOW 1
DEFINE I2C_HOLD 1
DEFINE CHAR_PACING 102

start:
B0 = 0
B1 = 0
pause 100
i2cwrite PORTB.0,PORTB.1,$36,$0E,[0]
pause 10
i2cwrite PORTB.0,PORTB.1,$36,$0E,[1]
pause 10
I2CREAD PORTB.0,PORTB.1,$36,$0E,[B0]
pause 10
I2Cwrite PORTB.0,PORTB.1,$36,$0F,[0]
pause 10
I2Cwrite PORTB.0,PORTB.1,$36,$0F,[1]
pause 10
I2CREAD PORTB.0,PORTB.1,$36,$0F,[B1]
pause 10
LCDOut $FE, 1, dec B1
LCDOut $FE, $C0, dec B0
goto start

Any help you can provide in this matter will be appreciated.

Well, from the datasheet I could not understand much about how to read data from the chip.

What are the $0F and $0E after $36 in your commands?

Also, are you sure you have connected correctly data and clock of the I2C bus from PIC to AS5600?

Ioannis

the data sheet address is a 7 bit address pbp uses 8 bit address
what are ic2writes for ?
they seem to be of no value that i can see
you defined sda and scl why not use them ?

more like

start:
I2CREAD SDA,SCL,$6C,$0E,[B0,B1]
LCDOut $FE, 1, dec B1
LCDOut $FE, $C0, dec B0
goto start

$36 is I2C address for AS5600
$0F and $0E address for low and high bytes from encoder.
I am pretty sure the data and clock are connected correctly. Also I pull them hight with 4.7k resistor.

what are ic2writes for ?
I thought that I need to send trigger first to AS5600 (Master mode), but I might be wrong.

Can I ask you why did you use $6C in read command? Shouldn't it be $36?

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$36 is I2C address for AS5600

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the data sheet address $36 is a 7 bit address pbp uses an 8 bit address scheme

Quote:

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I thought that I need to send trigger first to AS5600 (Master mode), but I might be wrong.

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You may well have to "configure" the device but for an i2c read transaction that is an unnecessary step

Quote:

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$0F and $0E address for low and high bytes from encoder.

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both registers can be read in a single transaction as i indicated

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Originally Posted by richard

the data sheet address $36 is a 7 bit address pbp uses an 8 bit address scheme

Does it mean that I can not communicate or I need to adjust the address?


You may well have to "configure" the device but for an i2c read transaction that is an unnecessary step

ok


both registers can be read in a single transaction as i indicated

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ok


Thank you.

I have used this one:
I2CREAD SDA,SCL,$6C,$0E,[B0,B1]
and it works. Thank you very much for your help

Glad to hear you got this working. I'll throw out a quick start I've been trying lately when interfacing to new chips for a basic frame work that gets me down the road quickly. I've been trying out OpenAi's Free chat bot.
This is what I entered in for your pic and the AS5600.

ChatBot Query: Write a PicBasic Pro program to read/write data from AS5600L-ASOM with the PIC18F4550 .

Output: To interface the AS5600L-ASOM magnetic rotary position sensor with the PIC18F4550 microcontroller using PICBASIC PRO, you need to set up I2C communication. The AS5600L-ASOM uses the I2C protocol to communicate with the microcontroller.

Here’s a sample program to read the angle data from the AS5600L-ASOM and write it to an output.

PICBASIC PRO Code

Code:

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' Define I2C pins
DEFINE I2C_SDA PORTC.4
DEFINE I2C_SCL PORTC.3

' AS5600L-ASOM I2C address (default 0x36 shifted for 7-bit addressing)
AS5600_ADDR CON $36

' AS5600L-ASOM registers
AS5600_ANGLE_H CON $0E
AS5600_ANGLE_L CON $0F

' Variables
angleH VAR BYTE
angleL VAR BYTE
angle VAR WORD

' Initialize I2C
I2CINIT

' Main Program
main:
    ' Read the high byte of the angle register
    I2CREAD AS5600_ADDR, AS5600_ANGLE_H, [angleH]
    PAUSE 10

    ' Read the low byte of the angle register
    I2CREAD AS5600_ADDR, AS5600_ANGLE_L, [angleL]
    PAUSE 10

    ' Combine high and low bytes to get the full angle value
    angle = angleH << 8
    angle = angle | angleL

    ' Convert angle to degrees (angle is 0-4095 representing 0-360 degrees)
    angle = (angle * 360) / 4096

    ' Add your code here to use the angle value (e.g., display on an LCD, send via serial, etc.)
    ' For example, send angle via UART
    SEROUT2 PORTC.6, 84, ["Angle: ", DEC angle, 13, 10]

    PAUSE 1000  ' Delay 1 second before next read

    GOTO main

END

---

Explanation
Define I2C Pins: Set the SDA and SCL pins for I2C communication.
AS5600L-ASOM I2C Address: The I2C address for the AS5600L-ASOM is 0x36. Note that some libraries expect the 7-bit address shifted for 8-bit communication.
AS5600L-ASOM Registers: Define the registers for reading the angle.
Variables: Declare variables to store the high and low bytes of the angle, and the combined angle value.
Initialize I2C: Use I2CINIT to initialize the I2C communication.

Main Program Loop:
Read the high byte and low byte of the angle register.
Combine the high and low bytes to get the full 12-bit angle value.
Convert the angle value to degrees.
Use the angle value as needed (e.g., send via UART for display).

Notes
Ensure pull-up resistors (typically 4.7k ohms) are connected to the SDA and SCL lines.
Adjust the SEROUT2 command for your specific UART configuration if needed.
The angle value from the AS5600L-ASOM is 12 bits, representing a range of 0-4095, which maps to 0-360 degrees.
This code provides a basic framework for interfacing the AS5600L-ASOM with a PIC18F4550 microcontroller using PICBASIC PRO. You can expand and modify it based on your specific requirements.

It's not perfect but can get some project started quickly as a reference.

Well, many times I tried to make ChatGPT understand that variable definition is special in PBP and different from other dialects of Basic.

And it finally got it!!! Amazing... this thing is indeed learning!

Of course needs more details on the prompt to make a useful program. Or at the end instead of detailed prompt, just write the program yourself :)

Ioannis

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And it finally got it!!! Amazing... this thing is indeed learning!

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i would not say that, the code given will never work and has at least three fundamental flaws
number one the i2c address is incorrect

Number two: With angle being 16bits and the raw value returned by the sensor ranging between 0 and 4095 this will not work great:

Code:

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' Convert angle to degrees (angle is 0-4095 representing 0-360 degrees)
    angle = (angle * 360) / 4096

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Both of you are absolutely right, but I was referring to the Variables definition, that were always defined wrong. Now it got it right.

I am convinced that it is getting better every time and maybe after a few months, it will correct those mistakes too.

And in general does not define the various FSR's unless you strictly ask it to do so.

Ioannis

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I am convinced that it is getting better every time

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not at all , when you see fundamental errors like this

Code:

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    ' Read the high byte of the angle register
    I2CREAD AS5600_ADDR, AS5600_ANGLE_H, [angleH]
    PAUSE 10


    ' Read the low byte of the angle register
    I2CREAD AS5600_ADDR, AS5600_ANGLE_L, [angleL]
    PAUSE 10

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if the read angle moves by 1 bit count in-between the reads then the read position error could up to +- 45 degrees [256 counts]

pbp i2c is glacially slow a 10ms pause in between reads wtf!, its just nonsense

Definetly will not take the job of software engineers in the near future. But it is getting better. And I suspect the free version is not that good for obvious reasons.

But paid AI does incredible job in other fields, like voice, image and video processing, that by definition is more complex than a I2C transaction. That is why I believe it can do much better that this PAUSE 10...!!!

Don't forget also that we are all beta testers and at the same time teachers of this beast...

Ioannis