Breakout I2C UART SPI AnalogRead AnalogWrite

[pennam]

Sorry guys @facchinm @Rocketct, but need some more advice here. Following yesterday discussion i wrote some lines of code:

• Going for nesting such as Breakout.I2C_0.begin() I think is not possible to declare objects into external file Objects.cpp cause they need to be inside BreakoutCarrierClass
• I2CX are used as define into STM32Hal so we need to use I2C_X
• PwmOut.h is not in the core so we cannot inherit from PwmOut object.
• For better readability i prefer to group objects in sub classes like BreakoutI2CClass, BreakoutUARTClass, BreakoutPWMClass , but this adds another nesting level and the result to the user will be Breakout.I2C.BUS_0.begin()

And now the real question, is there any C++ trick to avoid this double nesting?

[facchinm]

I'd go for option 2 (standalone objects) to avoid the second level of indirection as you perfectly noticed :slightly_smiling_face: Apart from this, I2C silk is different from all the other peripherals, so calling them I2C_X is perfectly fine

[pennam]

@facchinm @Rocketct i've updated the pr.

• I2C is working
• analogWrite on PWM pins works, but not on PWM3 (mbed crash) and not consistently on PWM4
• Need to test UARTS

One more question about pin naming: for internal usage such as I2C class initialization should we go for I2C_0(PH_8,PH_7) or I2C_0(digitalPinToPinName(I2C_SDA_0), digitalPinToPinName(I2C_SDA_1))

[facchinm]

I think I2C_0(PH_8,PH_7) is ok, it spares the reader from one level of indirection :slightly_smiling_face: About PWMs, were are they connected? We know one HRTIMER was not avvailable via mbed APIs (@Rocketct can you provide the code we used for I don't remember which project?) but all the others should be ok

[Rocketct]

sure was the PMC, @pennam here (https://github.com/bcmi-labs/AutomationCarrierLibrary/blob/master/src/MachineControl.h#L196-L323) the PWM code based on HRTIMER, in the class i made, I've used the same naming so you should find it already aligned with the PWM ones, here the example if you need https://github.com/bcmi-labs/AutomationCarrierLibrary/blob/master/examples/Analog_Out/Analog_Out.ino.

Last but important how to instance, one of that object and the difference with respect the mbed::PWM https://github.com/bcmi-labs/AutomationCarrierLibrary/blob/master/src/MachineControl.h#L329-L384

[pennam]

Status update:

• I2C working but .available() is returning always 72 because of mbed i2c_read() bug
• analogRead works
• analogWrite works but PWM4 and PWM8 cannot work together because are sharing the same timer channel (Confirmed). Minimum frequency increased to 770Hz due to HRTIM.
• SPI works, name will be SPI_0 as for I2C (SPI0 is an ST define)
• SDCARD works (on my breakout R1 was missing)
• UART works, flow control is disabled because it causes mbed crash
• PDM works

[sebromero]

Is there a reason why we want to adopt underscores for SPI and I2C while for UART we just append the number? e.g. UART1 vs I2C_0? Afaik in Arduino API we usually use camel-case without underscores. Same for functions. e.g. i2c_read() vs i2cRead(). https://www.arduino.cc/en/Reference/APIStyleGuide

[pennam]

We cannot use SPI0 and I2C0 because are already used as defines in ST mbed source files.

To access I2C functions i've reused Wire API so from sketch user needs to write:

Breakout.I2C_0.begin()
Breakout.I2C_0.beginTransmission()
Breakout.I2C_0.endTransmission()
Breakout.I2C_0.write()

The same for all other peripherals, i2c_read is an mbed API that needs to be fixed because has a bug, but there is no need to call it from sketch.

[Rocketct]

yes the macros without underscore are already defined on mbed's core so that name is the nearest as possible keeping the analogy with the silk

[sebromero]

Hmm, but we're using them as scoped variable names in BreakoutCarrierClass. Why can't we do Breakout.I2C0.begin()?

[pennam]

because I2C0 is a define and the preprocessor will replace it

[sebromero]

Ah, I see, actually I2C0 would work but I2C1 is defined :-D That's unfortunate.

[pennam]

For I2C issue i've submitted this patch https://github.com/ARMmbed/mbed-os/pull/14659 For UART flow control i'm working on a software implementation cause hw flow control is not available on that pins https://github.com/arduino/ArduinoCore-mbed/compare/master...pennam:sw_flow_control?expand=1

@facchinm should i wait/request a formal approval to merge this pr?

[facchinm]

LGTM!