[riot-devel] HIL testing

Hauke Petersen hauke.petersen at fu-berlin.de
Thu Nov 30 09:45:18 CET 2017

Hi Peter,

I think definition/implementation of a I2C slave interface/drivers is 
still wanted. But I found, that for the presented HIL use-case, a custom 
pin-banging i2c slave mock-up implementation is better suited, as it 
further allows us to intentionally trigger faulty bus behavior (not 
releasing the clock line, etc), which gives us even better control than 
using a hardware I2C slave unit for the test peer. When getting to 
testing the actual I2C slave implementations at some point, we would 
IMHO then also need a pin-banging version of a I2C master for testing...

But before jumping into the I2C slave discussion (and same goes of 
course for the SPI slave), I think it makes sense to lead all our 
efforts into the I2C master API remodeling first.


On 28.11.2017 09:21, Peter Kietzmann wrote:
> Hi Hauke,
> thanks for you efforts! This is great and really useful work. IMO it is
> the right direction, even though I always hoped to find a way around
> implementing our own I2C slave device. That's why I wanted to take this
> opportunity to ask around for other experiences with I2C (slave) test
> devices. Anyone, anything?
> Best
> Peter
> Am 27.11.2017 um 18:33 schrieb Hauke Petersen:
>> Hi everyone,
>> in today's developer meeting the discussion passed by the topic of HIL
>> testing once again, this time in the context of the upcoming re-modeling
>> of the I2C interface. Some weeks ago I had an idea for a simple HIL
>> setup for automatically testing perihp/i2c drivers, and I promised to
>> share it (although it is in very very early state). So here it is.
>> So the basic idea is to connect the I2C pins of the 'board-under-test'
>> (i2c master for now) to a 2nd board (lets call it 'test peer'), running
>> a fully controllable software i2c slave implementation. On the
>> device-under-test we simply run the 'tests/periph_i2c' app, that lets us
>> control the I2C master using shell commands (init/read/write incl
>> parameters). On the 'test peer' we run a programmable soft i2c client,
>> that offers shell commands expressing expectations, e.g. "expect 4 byter
>> [abcd] written to addr 0x23".
>> Now for creating an automated I2C test-suite, I imagine something
>> similar to our existing pyexpect scripts (testrunner), just with the
>> added capability of handling two clients. So the test script could look
>> something like this (mostly pseudocode...):
>> `PORT=/dev/ttyACM0 TESTPEER=/dev/ttyACM1 make hil-test`
>> triggers:
>> ```python
>> ...
>> def testfunc(testie, peer):
>>      ...
>>     # tell the 'test peer' to expect something to be written to addr 0x23
>> and respond with a NACK
>>      peer.sendline("expect_addr 0x23")
>>     # write a random byte the addr 0x23
>>      testie.sendline("w 0x23 a")
>>      # the 'test peer' will tell if it sees the expected address
>>      peer.expect("[SUCCESS]")
>>      # the 'device-under-test' should recognize the NACK
>>      testie.expect("error: no device with that address found on bus")
>>      # test writing (expect 4 bytes [affe] written to address 0x42)
>>      peer.sendline("expect_write 0x42 a f f e")
>>      testie.sendline("w 0x42 a f f e")
>>      peer.expect("[SUCCESS]")
>>      testie.expect("I2C_DEV(0): successfully wrote 4 bytes to the bus\n")
>>     ...
>>      # many many more test cases here, including simulation of badly
>> behaving slaves and bus recovery...
>> ```
>> I have sketched a I2C slave implementation to run on the 'test peer' in
>> [1] (under `tests/softi2ccli`). It is in no means production code, but a
>> quick prove of concept. But IMHO this would be a very easy and straight
>> forward way to have an automatic test-suite that would work on someones
>> desk for now.
>> Integration into the bigger picture would hopefully be easy doable, but
>> this not in the scope of this particular proposal here...
>> For now my goal would simply be to build a test suite for assisting with
>> the upcoming I2C remodeling to get some hands-on experience and speed up
>> the testing efforts for that task.
>> Cheers,
>> Hauke
>> [1] https://github.com/haukepetersen/RIOT/tree/add_softi2cli
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