i2c_software: Implementation of software i2c #6141

bigtreetech · 2023-03-27T09:55:42Z

Follow up #6130
Software I2C tested on STM32H7 with both BME280 and sh1106, The actual test results are normal.

The following are some results captured by the logic analyzer.

100KHz i2c read
100KHz i2c write
~~400KHz i2c read~~
~~400KHz i2c write~~

Note

~~The maximum rate in the .c source file is limited to 1MHz, and the actual rate captured by the logic analyzer is between 800KHz-1MHz~~ Speed fixed to 100KHz
Tested on Mega2560, it can control i2c devices normally, but even without the i2c_delay function, the occupancy rate of the mcu is still 100%, so it is not recommended to use software i2c on MCU like Mega2560

thijstriemstra · 2023-03-30T23:57:39Z

Tested on Mega2560, it can control i2c devices normally, but even without the i2c_delay function, the occupancy rate of the mcu is still 100%, so it is not recommended to use software i2c on MCU like Mega2560

Any other test results? e.g an Octopus board.

KevinOConnor

Thanks. As high-level feedback, the functionality seems useful. I have some comments on the implementation - see below.

Can you provide additional information on how this will be used? Is there a device that needs this support and requires high speed I2C access?

-Kevin

KevinOConnor · 2023-04-07T17:29:39Z

src/i2c_software.c

+        gpio_out_write(is->sda, b & 0x80);
+        b <<= 1;
+        i2c_delay(is->ticks);
+        gpio_out_write(is->scl, 1);
+        i2c_delay(is->ticks);
+        gpio_out_write(is->scl, 0);


To communicate over an I2C bus, the transmitter should transition between GND and high-Z states. This code is transitioning between GND and HIGH states. If the transmitter transitions to a HIGH state while the receiver is in a GND state it would result in a "short" on the wires that would consume power, generate heat, and possibly destabilize the board voltage.

I have written code to communicate with I2C devices using just GND/HIGH transitions (eg, klippy/extras/mcp4018.py). This change, though, may confuse users into thinking Klipper supports I2C on any device. I'm not sure that is a good idea.

Yeah, Theoretically this is a problem.
It would be perfect if there were a universal API to set GPIO as Open-Drain output, but some MCU (such as RP2040) do not seem to have the Open-Drain feature

Could the code transmit bits by switching between gpio_in_reset(is->sda_in, 1) and gpio_out_reset(is->sda_out, 0)?

I suspect the transfer rate would be slower, but it would hopefully not cause electrical problems.

Yeah, the transfer rate would be slower. Mainly affecting MCU with lower main frequencies such as STM32G0B1 64MHz.
The measured results are as follows

1 gpio_out_write gpio_in/out_reset

STM32G0B1 70KHz 30-40KHz

RP2040 84KHz 70KHz

For MCUs with high main frequencies like STM32H7, The impact is minimal.

src/i2c_software.c

bigtreetech · 2023-04-17T08:58:00Z

Tested on Mega2560, it can control i2c devices normally, but even without the i2c_delay function, the occupancy rate of the mcu is still 100%, so it is not recommended to use software i2c on MCU like Mega2560

Any other test results? e.g an Octopus board.

It can work normally in Octopus F4/H7 versions

KevinOConnor · 2023-05-11T18:58:59Z

Thanks. I guess my main question is - which users are expected to utilize this and what hardware is it expected that they will use it with? Is this just general functionality that some users may find useful or is there a specific hardware setup that requires this functionality?

In general I prefer to only add code when we have a general idea of who will be using it and what they use it for. (That way, I can get a better feel for the maintenance costs of the extra code relative to the functionality obtained by that new code.)

Cheers,
-Kevin

Signed-off-by: Alan.Ma from BigTreeTech tech@biqu3d.com

bigtreetech · 2023-05-23T04:14:11Z

Thanks. I guess my main question is - which users are expected to utilize this and what hardware is it expected that they will use it with? Is this just general functionality that some users may find useful or is there a specific hardware setup that requires this functionality?

In general I prefer to only add code when we have a general idea of who will be using it and what they use it for. (That way, I can get a better feel for the maintenance costs of the extra code relative to the functionality obtained by that new code.)

Cheers, -Kevin

This requirement is raised by some of our customers who want to connect BME280 temperature and humidity sensors to our motherboard (such as Octopus max ez). There is no hardware i2c port reserved on the motherboard, but there are many GPIO

KevinOConnor · 2023-06-01T19:51:08Z

Okay, thanks. In general, it looks fine to me. I'll look to commit early next week.

-Kevin

KevinOConnor · 2023-06-08T00:55:52Z

Thanks.

-Kevin

JamesH1978 · 2023-06-08T12:02:06Z

This looks to break smaller STM32 builds like the 042 with an error of

Linking out/klipper.elf /usr/lib/gcc/arm-none-eabi/10.3.1/../../../arm-none-eabi/bin/ld: out/klipper.elf section.text' will not fit in region rom' /usr/lib/gcc/arm-none-eabi/10.3.1/../../../arm-none-eabi/bin/ld: region rom' overflowed by 904 bytes
collect2: error: ld returned 1 exit status`

Seems to push it over the flash size

Thanks
James

@KevinOConnor @bigtreetech

JamesH1978 · 2023-06-08T12:12:39Z

seems changing line 10 of Kconfig from select HAVE_GPIO_I2C if !MACH_STM32F031 to select HAVE_GPIO_I2C if !MACH_STM32F031 && !MACH_STM32F042 fixes it at least for the 042, i havent tested other STM32F0XX mcu's

Lefuneste83 · 2023-06-08T14:54:22Z

seems changing line 10 of Kconfig from select HAVE_GPIO_I2C if !MACH_STM32F031 to select HAVE_GPIO_I2C if !MACH_STM32F031 && !MACH_STM32F042 fixes it at least for the 042, i havent tested other STM32F0XX mcu's

This seems to allow compilation of FW for STM32F042. I have one in a Voron 0 display board. But the commit 645a1b seems to break i2c communication nonetheless. I have made several attempts, including a complete reinstall of klipper, but they all failed and I had to rollback to previous commit, which works without a problem, both in compiling FW and communication with the display board.

Protocol error
Traceback (most recent call last):
  File "/home/pi/klipper/klippy/klippy.py", line 180, in _connect
    cb()
  File "/home/pi/klipper/klippy/mcu.py", line 753, in _connect
    self._send_config(None)
  File "/home/pi/klipper/klippy/mcu.py", line 683, in _send_config
    cb()
  File "/home/pi/klipper/klippy/extras/bus.py", line 177, in build_config
    self.i2c_write_cmd = self.mcu.lookup_command(
  File "/home/pi/klipper/klippy/mcu.py", line 873, in lookup_command
    return CommandWrapper(self._serial, msgformat, cq)
  File "/home/pi/klipper/klippy/mcu.py", line 84, in __init__
    self._cmd = msgparser.lookup_command(msgformat)
  File "/home/pi/klipper/klippy/msgproto.py", line 315, in lookup_command
    self._error("Unknown command: %s", msgname)
  File "/home/pi/klipper/klippy/msgproto.py", line 243, in _error
    raise error(self.warn_prefix + (msg % params))
msgproto.error: mcu 'display': Unknown command: i2c_write

JamesH1978 · 2023-06-08T15:15:28Z

then my commit/solution may be just a sticking plaster for other problems caused by this commit

KevinOConnor · 2023-06-08T19:07:30Z

See #6244 for code to optionally disable software i2c (and other features) on chips with small flash sizes.

-Kevin

JamesH1978 · 2023-06-12T18:56:01Z

This also seems to break some rp2040 boards, at least a couple of SB2040 mellow owners have tmc uart issues on this commit, that i have seen on the discord

Thanks
James

Sineos · 2023-06-12T18:58:15Z

Also ref https://klipper.discourse.group/t/possible-bug-in-recent-commit/8921

Signed-off-by: Alan.Ma from BigTreeTech <tech@biqu3d.com>

bigtreetech force-pushed the software_i2c branch from a74c6d1 to fdc1c24 Compare March 28, 2023 02:27

KevinOConnor self-assigned this Apr 5, 2023

KevinOConnor reviewed Apr 7, 2023

View reviewed changes

bigtreetech force-pushed the software_i2c branch 4 times, most recently from 8f1e835 to 55b5e92 Compare April 17, 2023 07:50

bigtreetech force-pushed the software_i2c branch from c4f06e3 to 2410560 Compare May 22, 2023 11:28

bigtreetech added 4 commits May 22, 2023 19:28

i2c_software: Implementation of software i2c

4433848

Signed-off-by: Alan.Ma from BigTreeTech tech@biqu3d.com

Fixed speed to 100KHz, avoid division during runtime

c57006d

use gpio_**_reset, avoid gpio_**_setup call nor multiple times

5625a36

debug: Testing speed

e2cf917

bigtreetech force-pushed the software_i2c branch from 2410560 to e2cf917 Compare May 22, 2023 11:28

KevinOConnor merged commit 645a1b8 into Klipper3d:master Jun 8, 2023

bigtreetech deleted the software_i2c branch June 8, 2023 01:53

Lesorin pushed a commit to Lesorin/klipper that referenced this pull request Jul 13, 2023

i2c_software: Implementation of software i2c (Klipper3d#6141)

e4f8fbd

Signed-off-by: Alan.Ma from BigTreeTech <tech@biqu3d.com>

Lesorin pushed a commit to Lesorin/klipper that referenced this pull request Jul 13, 2023

i2c_software: Implementation of software i2c (Klipper3d#6141)

f067511

Signed-off-by: Alan.Ma from BigTreeTech <tech@biqu3d.com>

rogerlz referenced this pull request in DangerKlippers/danger-klipper Dec 19, 2023

i2c_software: Implementation of software i2c (#6141)

201baa1

Signed-off-by: Alan.Ma from BigTreeTech <tech@biqu3d.com>

github-actions bot locked and limited conversation to collaborators Jun 12, 2024

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

i2c_software: Implementation of software i2c #6141

i2c_software: Implementation of software i2c #6141

bigtreetech commented Mar 27, 2023 •

edited

Loading

thijstriemstra commented Mar 30, 2023

KevinOConnor left a comment

KevinOConnor Apr 7, 2023

bigtreetech Apr 17, 2023

KevinOConnor May 11, 2023

bigtreetech May 23, 2023

bigtreetech commented Apr 17, 2023

KevinOConnor commented May 11, 2023

bigtreetech commented May 23, 2023

KevinOConnor commented Jun 1, 2023

KevinOConnor commented Jun 8, 2023

JamesH1978 commented Jun 8, 2023

JamesH1978 commented Jun 8, 2023

Lefuneste83 commented Jun 8, 2023

JamesH1978 commented Jun 8, 2023

KevinOConnor commented Jun 8, 2023

JamesH1978 commented Jun 12, 2023

Sineos commented Jun 12, 2023

i2c_software: Implementation of software i2c #6141

i2c_software: Implementation of software i2c #6141

Conversation

bigtreetech commented Mar 27, 2023 • edited Loading

Note

thijstriemstra commented Mar 30, 2023

KevinOConnor left a comment

Choose a reason for hiding this comment

KevinOConnor Apr 7, 2023

Choose a reason for hiding this comment

bigtreetech Apr 17, 2023

Choose a reason for hiding this comment

KevinOConnor May 11, 2023

Choose a reason for hiding this comment

bigtreetech May 23, 2023

Choose a reason for hiding this comment

bigtreetech commented Apr 17, 2023

KevinOConnor commented May 11, 2023

bigtreetech commented May 23, 2023

KevinOConnor commented Jun 1, 2023

KevinOConnor commented Jun 8, 2023

JamesH1978 commented Jun 8, 2023

JamesH1978 commented Jun 8, 2023

Lefuneste83 commented Jun 8, 2023

JamesH1978 commented Jun 8, 2023

KevinOConnor commented Jun 8, 2023

JamesH1978 commented Jun 12, 2023

Sineos commented Jun 12, 2023

bigtreetech commented Mar 27, 2023 •

edited

Loading