TMS320F280041: TMS320F28xxx 8bit support

Lennart Gardian2

Part Number: TMS320F280041
Other Parts Discussed in Thread: TMS320F2806

Hi there,

At the beginning of our project I realised that the TMS320F280041 has no 8bit support. "Not a problem" I thought but now where I would like to reuse old code we used on different architectures I start to realize the problem.

So few questions arised: Does really no TMS320F28xxx support 8 bit? We used to have a TMS320F2806 which did support 8bit but in the stdint.h that comes with the c2000_20.2.2.LTS compiler it seems like even the 2806 wouldn't have an 8bit support with that paticular compiler?
If there is any TI MCU with an ePWM, at least 100MHz Clk, roughly 50kB FLash and 50kB RAM, a bunch of 12bit ADCs and 8bit support I would love to hear about.

Secondly I am wondering of how TI came to the idea to drop 8bit variables? Aren't several TI customers going nuts on that decision? Don't they all have their bootloaders, UART coms and what not implemented with 8bit variables that they now have to overhaul just because there suddenly is one out of a million chips that doesn't have 8bit variables? I just can't wrap my head around this.

Thanks in advance for your support!

Lennart

over 5 years ago

0 Sira Rao80 over 5 years ago

TI__Mastermind 28135 points

Lennart,

No there is no native 8-bit support in the TMS320F28xx family. The compiler would automatically convert char types to 16-bit fields.

I will let product marketing address your remaining questions.

Thanks,

Sira

0 ChrisClearman over 5 years ago

TI__Guru** 119680 points

No, there is not a TI MCU that meets the requirements + 8-bit

To be honest, I can't think of a time this was ever brought up as an issue in 20+ years of shipping F28x based products. I assume it must have been at least an inconvenience early on.

0 Lennart Gardian2 over 5 years ago in reply to ChrisClearman

Intellectual 270 points

Hi Chris,

interesting this never came up. Is the 280049 really being shipped 20+ years now? I'm asking because about 10 years ago we switched to the 2806 which did have an 8 bit support.

Anyways, thanks for the answer. Still can't believe nobody complained about this though.

+1 Lori Heustess over 5 years ago in reply to Lennart Gardian2

TI__Guru* 93800 points

Lennart Gardian2 said:
Is the 280049 really being shipped 20+ years now?

Hi Lennart, A quick clarification. The C28x CPU-based products have been shipping for more than 20 years. The specific device (F28004x) has this same CPU (plus instruction additions for floating-point).

Lennart Gardian2 said:
I'm asking because about 10 years ago we switched to the 2806 which did have an 8 bit support.

The C28x CPU byte has always been 16-bits. This includes the CPU on F2806 products.

This was a decision made long ago (20+ years ago) and I would say one of the things I would change about the CPU if it was something easy to do.

There are some specific instructions and intrinsic that one can use to access bytes. This, however, does not change the underlying architecture, unfortunately. Perhaps these were used on the F2806 product you developed?

https://software-dl.ti.com/ccs/esd/documents/c2000_byte-accesses-with-the-c28x-cpu.html

Best Regards

Lori

0 Lennart Gardian2 over 5 years ago in reply to Lori Heustess

Intellectual 270 points

Thanks for clarifying. I digged a little deeper on the old project and I realised they just use a typedef from char to uint8_t and hence their byte is actually 16bit. Sure that works in 99% of the cases and obviously it worked for the old project.

Anyways, more reasons like the missing C++11 support make us leave the C28x architecture. Even though I like the price of them.

Thanks,

Lenn

0 Sira Rao80 over 5 years ago in reply to Lennart Gardian2

TI__Mastermind 28135 points

Lennart,

Are there any particular aspects of C++11 support that you are looking for?

Thanks,

Sira

0 Lennart Gardian2 over 5 years ago in reply to Sira Rao80

Intellectual 270 points

Hi Sira,

not for me in paticular. We just have the issue that we're trying to use the same libs in all our devices. Serial communication for instance is a very important lib that we basically use in all devices. Generally we use Arm processor and since the according compiler is a C++11 compiler, several features were used which are not available on C++03 compilers. Adjusting the com lib for the C28x family would be an option but for maintainance reasons is not quite what some people would want.

0 Sira Rao80 over 5 years ago in reply to Lennart Gardian2

TI__Mastermind 28135 points

Thanks Lennart.

C2000™︎ microcontrollers

C2000 microcontrollers forum

TMS320F280041: TMS320F28xxx 8bit support