LPC8xx port

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Re: LPC8xx port

Postby Giovanni » Thu May 22, 2014 3:23 pm

The github repository is a clone, better submitting patches that I can apply on a subversion checkout.

Giovanni

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jcw
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Re: LPC8xx port

Postby jcw » Thu May 22, 2014 4:50 pm

Here's a first attempt. Most of the boring work is done, I think. The missing bit is the alarm code, which I assume is for the new tickless functionality. The files added are as follows, I think it's close to the conventions adopted for 3.x:

Code: Select all

 chibios-lpc (master +) ➤ git status
# On branch master
# Changes to be committed:
#   (use "git reset HEAD <file>..." to unstage)
#
#   new file:   demos/LPC/RT-LPC812-EA_MAX/Makefile
#   new file:   demos/LPC/RT-LPC812-EA_MAX/chconf.h
#   new file:   demos/LPC/RT-LPC812-EA_MAX/halconf.h
#   new file:   demos/LPC/RT-LPC812-EA_MAX/main.c
#   new file:   demos/LPC/RT-LPC812-EA_MAX/mcuconf.h
#   new file:   demos/LPC/RT-LPC812-EA_MAX/readme.txt
#   new file:   os/common/ports/ARMCMx/compilers/GCC/ld/LPC812.ld
#   new file:   os/common/ports/ARMCMx/devices/LPC8xx/cmparams.h
#   new file:   os/ext/CMSIS/NXP/lpc8xx.h
#   new file:   os/ext/CMSIS/NXP/system_LPC8xx.h
#   new file:   os/hal/ports/LPC/LPC8xx/ext_lld.c
#   new file:   os/hal/ports/LPC/LPC8xx/ext_lld.h
#   new file:   os/hal/ports/LPC/LPC8xx/ext_lld_isr.c
#   new file:   os/hal/ports/LPC/LPC8xx/ext_lld_isr.h
#   new file:   os/hal/ports/LPC/LPC8xx/gpt_lld.c
#   new file:   os/hal/ports/LPC/LPC8xx/gpt_lld.h
#   new file:   os/hal/ports/LPC/LPC8xx/hal_lld.c
#   new file:   os/hal/ports/LPC/LPC8xx/hal_lld.h
#   new file:   os/hal/ports/LPC/LPC8xx/pal_lld.c
#   new file:   os/hal/ports/LPC/LPC8xx/pal_lld.h
#   new file:   os/hal/ports/LPC/LPC8xx/platform.mk
#   new file:   os/hal/ports/LPC/LPC8xx/serial_lld.c
#   new file:   os/hal/ports/LPC/LPC8xx/serial_lld.h
#   new file:   os/hal/ports/LPC/LPC8xx/spi_lld.c
#   new file:   os/hal/ports/LPC/LPC8xx/spi_lld.h
#   new file:   os/hal/ports/LPC/LPC8xx/st_lld.h
#   new file:   os/nil/ports/ARMCMx/compilers/GCC/mk/port_lpc8xx.mk
#


Does this help?

-jcw

UPDATE: more patches (mostly osal stuff, which I had overlooked), resulting compile now ends with this:

Code: Select all

[...]
Compiling ext_lld_isr.c
Compiling board.c
Compiling main.cpp
Linking build/ch.elf
/var/folders/zj/b87xh4pj56v1g9nsvc1q6k580000gn/T//cc3f0EUA.ltrans0.ltrans.o: In function `stInit':
/Users/jcw/Desktop/new-code/jeeapps/blink-lpc812ea/../../chibios/os/hal/src/st.c:66: undefined reference to `st_lld_init'
collect2: error: ld returned 1 exit status
make: *** [build/ch.elf] Error 1


New "lpc3a" patch attached, includes all of the first patch as well.
Attachments
lpc3a.patch.gz
(31.03 KiB) Downloaded 143 times
lpc3.patch.gz
(30.99 KiB) Downloaded 140 times
Last edited by jcw on Thu May 22, 2014 5:33 pm, edited 1 time in total.

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Re: LPC8xx port

Postby Giovanni » Thu May 22, 2014 5:28 pm

Sure it does, theShed can commit it when ready.

When porting just make sure to take Makefile, chconf.h and halconf.h from 3.0, there are differences.

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Re: LPC8xx port

Postby jcw » Thu May 22, 2014 5:36 pm

Ok, great. I'll leave this for now - looking forward to get this going. After a first example, next LPC's should become easier.

-jcw

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Re: LPC8xx port

Postby jcw » Thu May 22, 2014 7:23 pm

Trying to figure out how to add the missing st_lld.c logic, but I'm afraid I don't get it. Tickless means: "don't just fire ticks periodically and all the time, instead figure out when the next interrupt is needed, and set up a timeout for exactly that point in time", right? So the idea is to make some (any?) timer do the work by setting up a one-shot event?

How does ChibiOS deal with time? In 3.0, the STM32 code picks a timer and uses that for the ST (SysTick?).
Why isn't the SysTick hardware being used, which is present in every ARM chip?

Both STM32 and LPC have general-purpose timers (with quite different hardware implementations).
In the case of the LPC8xx, there's a 4-channel "Multi-Rate Timer" (MRT), which is not tied to any I/O pins.
It doesn't have compare registers, just countdowns (either one-shot or repetitive).
I suspect that it'll accumulate some lost ticks when set to different values, but that should be ok for a first attempt.

-jcw

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Re: LPC8xx port

Postby Giovanni » Thu May 22, 2014 7:39 pm

In tickless mode the system time is no more a variable incremented by the system tick, it is an hardware register incremented at a fixed rate. A comparator register generates an interrupt when the next deadline is reached. The virtual timers scheduler recalculates the next deadline each time a tick is processed.

The Cortex systick timer is not able to do that: it is only 24 bits large, does not have a prescaler and it is decremented instead of incremented.

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Re: LPC8xx port

Postby jcw » Thu May 22, 2014 8:13 pm

Ok, thx. In that case, the LPC8xx may not be able to work tickless - its MRT is 32-bit, but countdown-only and no pre-scaler. Perhaps it could be tricked by using negated/complemented values everywhere?

I just found the logic for the OSAL_ST_MODE_PERIODIC mode, i.e. SysTick-based after all.
Hacking around to see if I can get that simpler case to work :)

-jcw

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Re: LPC8xx port

Postby jcw » Thu May 22, 2014 8:42 pm

Success: here's the second part. The demo now compiles cleanly and blinks the RGB LEDs with the proper timing on an LPC812-MAX board. Apply the attached "lpc3a2" patch after the "lpc3a" patch (and ignore that first "lpc3" patch). There are some loose ends, marked with "//xxx" in the code. This is running in periodic mode, not tickless.

-jcw
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lpc3a2.patch.gz
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Re: LPC8xx port

Postby theShed » Sun May 25, 2014 8:31 pm

Thanks for this.
I will try to take a look asap, unfortunately work keeps getting in the way - I have a looming 1st June deadline and about three weeks work left to do...

--
mike

PS. you can submit git pull requests to me, I work in git and use git-svn to push changes to SVN

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Re: LPC8xx port

Postby jcw » Sun May 25, 2014 8:43 pm

Thx. No rush - work comes first. Do you want to update your TheShed/ChibiOS "kernel_3_dev" branch first, and let me submit diffs against that? Otherwise please let me know against which github checkout you want me to submit these changes, and I'll clone and try to come up with a clean diff.

-jcw


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