i2c bus hangs in master RPi access to MSP430G uC ~1 in 1000 accesses





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... resetting the MSP430 clears the hung state. I've slowed down the i2c clock freq, beefed up the PSupply, changed pull-up resistors - no change. However I made the "errors" increase significantly by busying the ARM with 2 calculation-intensive programs. I use Python in RPi, using smbus, SMBUS and
i2c_LCD_driver and try/except routines in the RPi to catch the bad access and reset the MSP - after that, accesses every 5 seconds continue fine until the next hang, ~1000 accesses later. I use C for the ISRs to manage interrupts in the MSP430.



I know both devices have hardware state machines that manage the i2c. Given that I can hang the bus by overworking the RPi, my suspicion was/is the implementation of the canned i2c python code. Is anyone aware of any weird
stuff about the Broadcom Serial Controller (BSC) i2c controller in the ARM that would hang a slave's state machine based on busy-ness of the OS managing the BSC ... or other cases of very intermittent bus hangs ?









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    ... resetting the MSP430 clears the hung state. I've slowed down the i2c clock freq, beefed up the PSupply, changed pull-up resistors - no change. However I made the "errors" increase significantly by busying the ARM with 2 calculation-intensive programs. I use Python in RPi, using smbus, SMBUS and
    i2c_LCD_driver and try/except routines in the RPi to catch the bad access and reset the MSP - after that, accesses every 5 seconds continue fine until the next hang, ~1000 accesses later. I use C for the ISRs to manage interrupts in the MSP430.



    I know both devices have hardware state machines that manage the i2c. Given that I can hang the bus by overworking the RPi, my suspicion was/is the implementation of the canned i2c python code. Is anyone aware of any weird
    stuff about the Broadcom Serial Controller (BSC) i2c controller in the ARM that would hang a slave's state machine based on busy-ness of the OS managing the BSC ... or other cases of very intermittent bus hangs ?









    share







    New contributor




    JoeM is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
    Check out our Code of Conduct.























      3












      3








      3


      1






      ... resetting the MSP430 clears the hung state. I've slowed down the i2c clock freq, beefed up the PSupply, changed pull-up resistors - no change. However I made the "errors" increase significantly by busying the ARM with 2 calculation-intensive programs. I use Python in RPi, using smbus, SMBUS and
      i2c_LCD_driver and try/except routines in the RPi to catch the bad access and reset the MSP - after that, accesses every 5 seconds continue fine until the next hang, ~1000 accesses later. I use C for the ISRs to manage interrupts in the MSP430.



      I know both devices have hardware state machines that manage the i2c. Given that I can hang the bus by overworking the RPi, my suspicion was/is the implementation of the canned i2c python code. Is anyone aware of any weird
      stuff about the Broadcom Serial Controller (BSC) i2c controller in the ARM that would hang a slave's state machine based on busy-ness of the OS managing the BSC ... or other cases of very intermittent bus hangs ?









      share







      New contributor




      JoeM is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.












      ... resetting the MSP430 clears the hung state. I've slowed down the i2c clock freq, beefed up the PSupply, changed pull-up resistors - no change. However I made the "errors" increase significantly by busying the ARM with 2 calculation-intensive programs. I use Python in RPi, using smbus, SMBUS and
      i2c_LCD_driver and try/except routines in the RPi to catch the bad access and reset the MSP - after that, accesses every 5 seconds continue fine until the next hang, ~1000 accesses later. I use C for the ISRs to manage interrupts in the MSP430.



      I know both devices have hardware state machines that manage the i2c. Given that I can hang the bus by overworking the RPi, my suspicion was/is the implementation of the canned i2c python code. Is anyone aware of any weird
      stuff about the Broadcom Serial Controller (BSC) i2c controller in the ARM that would hang a slave's state machine based on busy-ness of the OS managing the BSC ... or other cases of very intermittent bus hangs ?







      i2c





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          I've slowed down the i2c clock freq




          I am using RPi3B+ stretch 2019apr python 3.5.3.



          I surprisingly and sadly experienced, and read that Rpi3B+ stretch python 3.5x I2C is buggy.



          I could never have slowed down the default I2C 100kHz. I tried to change speed up to 400kHz and down to 50kHz. But hardware did not respond - no nothing changed. :(



          I read that it is a hardware bug. Are you sure you have actually successfully changed the speed? I vaguely remember that I could indeed change the speed when I was in jessie or earlier days.



          I also found that python 3.5.3 block read does not fully implement to entertain all the parameter patterns. My projects were "hung" and much time wasted. :(



          I am anxiously waiting for the coming soon Rpi4 to hopefully resume my couple of long stalled I2C related projects. In the meaning time I am switching to SPI (I2C MCP23017 to SPI MCP23S17, etc)



          Update 2019apr21hkt1156



          I did try smbus2 but sadly found other compatibility problems.



          References



          RASPBERRY PI3 I2C BAUD RATE SETTING Postby samtal » 2018-Aug-04 Sat 1:45 pm



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            I've slowed down the i2c clock freq




            I am using RPi3B+ stretch 2019apr python 3.5.3.



            I surprisingly and sadly experienced, and read that Rpi3B+ stretch python 3.5x I2C is buggy.



            I could never have slowed down the default I2C 100kHz. I tried to change speed up to 400kHz and down to 50kHz. But hardware did not respond - no nothing changed. :(



            I read that it is a hardware bug. Are you sure you have actually successfully changed the speed? I vaguely remember that I could indeed change the speed when I was in jessie or earlier days.



            I also found that python 3.5.3 block read does not fully implement to entertain all the parameter patterns. My projects were "hung" and much time wasted. :(



            I am anxiously waiting for the coming soon Rpi4 to hopefully resume my couple of long stalled I2C related projects. In the meaning time I am switching to SPI (I2C MCP23017 to SPI MCP23S17, etc)



            Update 2019apr21hkt1156



            I did try smbus2 but sadly found other compatibility problems.



            References



            RASPBERRY PI3 I2C BAUD RATE SETTING Postby samtal » 2018-Aug-04 Sat 1:45 pm



            / to continue, ...






            share|improve this answer






























              1















              I've slowed down the i2c clock freq




              I am using RPi3B+ stretch 2019apr python 3.5.3.



              I surprisingly and sadly experienced, and read that Rpi3B+ stretch python 3.5x I2C is buggy.



              I could never have slowed down the default I2C 100kHz. I tried to change speed up to 400kHz and down to 50kHz. But hardware did not respond - no nothing changed. :(



              I read that it is a hardware bug. Are you sure you have actually successfully changed the speed? I vaguely remember that I could indeed change the speed when I was in jessie or earlier days.



              I also found that python 3.5.3 block read does not fully implement to entertain all the parameter patterns. My projects were "hung" and much time wasted. :(



              I am anxiously waiting for the coming soon Rpi4 to hopefully resume my couple of long stalled I2C related projects. In the meaning time I am switching to SPI (I2C MCP23017 to SPI MCP23S17, etc)



              Update 2019apr21hkt1156



              I did try smbus2 but sadly found other compatibility problems.



              References



              RASPBERRY PI3 I2C BAUD RATE SETTING Postby samtal » 2018-Aug-04 Sat 1:45 pm



              / to continue, ...






              share|improve this answer




























                1












                1








                1








                I've slowed down the i2c clock freq




                I am using RPi3B+ stretch 2019apr python 3.5.3.



                I surprisingly and sadly experienced, and read that Rpi3B+ stretch python 3.5x I2C is buggy.



                I could never have slowed down the default I2C 100kHz. I tried to change speed up to 400kHz and down to 50kHz. But hardware did not respond - no nothing changed. :(



                I read that it is a hardware bug. Are you sure you have actually successfully changed the speed? I vaguely remember that I could indeed change the speed when I was in jessie or earlier days.



                I also found that python 3.5.3 block read does not fully implement to entertain all the parameter patterns. My projects were "hung" and much time wasted. :(



                I am anxiously waiting for the coming soon Rpi4 to hopefully resume my couple of long stalled I2C related projects. In the meaning time I am switching to SPI (I2C MCP23017 to SPI MCP23S17, etc)



                Update 2019apr21hkt1156



                I did try smbus2 but sadly found other compatibility problems.



                References



                RASPBERRY PI3 I2C BAUD RATE SETTING Postby samtal » 2018-Aug-04 Sat 1:45 pm



                / to continue, ...






                share|improve this answer
















                I've slowed down the i2c clock freq




                I am using RPi3B+ stretch 2019apr python 3.5.3.



                I surprisingly and sadly experienced, and read that Rpi3B+ stretch python 3.5x I2C is buggy.



                I could never have slowed down the default I2C 100kHz. I tried to change speed up to 400kHz and down to 50kHz. But hardware did not respond - no nothing changed. :(



                I read that it is a hardware bug. Are you sure you have actually successfully changed the speed? I vaguely remember that I could indeed change the speed when I was in jessie or earlier days.



                I also found that python 3.5.3 block read does not fully implement to entertain all the parameter patterns. My projects were "hung" and much time wasted. :(



                I am anxiously waiting for the coming soon Rpi4 to hopefully resume my couple of long stalled I2C related projects. In the meaning time I am switching to SPI (I2C MCP23017 to SPI MCP23S17, etc)



                Update 2019apr21hkt1156



                I did try smbus2 but sadly found other compatibility problems.



                References



                RASPBERRY PI3 I2C BAUD RATE SETTING Postby samtal » 2018-Aug-04 Sat 1:45 pm



                / to continue, ...







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