Tiva equivalent of Stellaris LM3S478

Hello Pete

Go to the bottom of the following link.

http://www.ti.com/lsds/ti/microcontrollers_16-bit_32-bit/c2000_performance/control_automation/tm4c12x/overview.page

There is a web application for equivalent LM3S parts. Please do download the equivalent TM4C123 data sheet and compare the pin out and features/

Regards

Amit

Pete Beech said:

would need either no changes or minimal changes to existing board design and/or firmware?

For faster answer - no/minimal changes to existing board design is NOT possible.  You'll have to layout/spin a new board.  Our small tech group has enjoyed this process 3 times...

As to firmware - while vendor is unlikely to sanction - we've migrated from LX4F to several TM4C devices - and in each case kept our past, StellarisWare library - and in our case all appears well!  Note that this holds true for the TM4C123 devices - software changes are encountered should you employ the TM4C129 family.  (StellarisWare unlikely to (fully) succeed w/that class device...)

The LX4F and TM4C123 was the transition point from Stellaris to Tiva, they are basically different revisions of the same chip with different markings.  Hence transition on that platform LX4F to TM4C is pretty simple and keeping StellarisWare running on a TM4C123 is acceptable provided you don't expect support or bug fixes from TI. 

From LM3S to TM4C may be a bit more involved depending on which peripherals you use.  For most peripherals it is just renaming things from unsigned long (ul prefix) to uint32_t (ui32 prefix). 

Regardless likely to simpler on software than changing to a different MCU vendor. 

The hardware delta is a bit more complex and will require significant board changes. 

for more information on the software migration see this application note

www.ti.com/lit/an/spma050a/spma050a.pdf

Hardware guidelines for TM4C123 (would also apply to LX4F)

www.ti.com/lit/an/spma059/spma059.pdf

Hardware Guidelines for TM4C129

www.ti.com/lit/an/spma056/spma056.pdf

INTEGRIS Dexter said:

keeping StellarisWare running on a TM4C123 is acceptable provided you don't expect support or bug fixes from TI. 

Let the record (clearly) reveal that StellarisWare, being far more mature & focused, has not experienced, "bugs" - especially the most recent, 3-4 revisions.  (last one 10636 - our belief)  So - any expectation of support for "bug fixes" - targeting long proven StellarisWare - appears a, "logical fallacy." (i.e. straw-man)

As you mention, "bugs" have those not arrived - and in cascade/multiple - w/rebrandWare?  In fact even the humble System Clock function has suffered.  Thus - the recommendation to employ, "tried/true" (i.e. StellarisWare) appears a wise choice for our firm - and perhaps migrating poster - too...

I won't argue against using proven software.  :).

For clarity and precision... 10636 is the last LM3S version.  9453 was the last (and only I believe) version that explicitly included both the LM3S and LX4F (aka LM4F).

http://www.ti.com/tool/sw-lm3s

Thanks for all the replies - really useful information.

cb1- said:

Note that this holds true for the TM4C123 devices - software changes are encountered should you employ the TM4C129 family.  (StellarisWare unlikely to (fully) succeed w/that class device...)

Amit - thanks - I used the tool to recommend an upgrade path, and it came up with the TM4C123GE6. However the LM3S478 has 64K SRAM, and the TM4C123GE6 only has 32K - and I can't find a model with 64KB. Obviously I'll need to check whether we really need the 64K, or whether we can't reduce the footprint needed, but disappointing there doesn't seem to be a 64K TMC4123.

This could mean that we have to choose one from the TM4C129 family, but the fact that StellarisWare might not succeed, as cb1 mentioned, is a bit concerning.

Hello Pete,

I can understand having half the RAM may be a problem and switching to TM4C129 which has a 256K SRAM but would require migration from StellarisWare to TIVAWare might bring another set of challenges.

But we can support your transition as we have done in the past.

Regards

Amit

Clearly you're forced into a board spin - pity that.  I've just checked Digi-Key - zero LM3S3748 devices in stock and they show 1K pc minimum order restriction - double pity.

There's an indirect means to add RAM which we've past used to, "beef up" the 32KB SRAM w/in our LX4F.  Via use of an FPGA/CPLD or Graphic LCD Controller - you can employ the (rather limited) 8 bit Stellaris/Tiva MCU (when a simpler, less costly/smaller, non-EPI Bus device is employed) to interface to an external RAM.  Even though the data bus is limited to 8 bits - the Lcd Controller is able to generate a multi-byte, SRAM Address.  Beyond this one, bi-directional port dedication - you will require control & strobe signals - (suspect 4) from a 2nd port.  So - you are trading nearly two 8 bit ports for added SRAM - this may or may not work for your application.  Note that the Lcd Controller has some "smarts" - after setting a start address - all subsequent reads/writes cause auto-increment/decrement of the address - easing your effort. 

Now - should your App require (or benefit from) a graphic or TFT display - the ability to "steal" such RAM from an over-sized LCD Controller - may well be your answer!  (i.e. such works nicely for us - enables our use of lower cost - less complex (pin reduced) M4 MCUs and our harvest of great expanse of external SRAM - built in (i.e. "free" w/in the Lcd controller))  We acknowledge that most all external SRAM access is not as quick/efficient as on-MCU - but that on-MCU choice has been reduced by 50% (your case) - and still unexplained - by powers here...

Blasphemy here - but there are Cortex M4s which do reach to 64KB (and far beyond) but will require new SW study/effort as well as board spin...  By far - your procurement (beg/borrow) of original LM3S3748 is your best path - I'd make every effort - that direction...