| ??? 04/30/05 08:29 Read: times |
#92636 - Sure its fair Responding to: ???'s previous message |
For sure, doing pre-emptive task switching with the 8051 can be limited by the 256 byte stack, but that doesn't preclude you from doing it. Even though Z80 and 6800 are 'real' cpus - they take a few cycles to do a context switch as would a 8051. How much 'real time' does it take a 8051 to save the cpu state to xram? then factor in how fast a lot of the newer derivatives are and we're not talking that much. The issue of 'ease' is a touchy one - we could bring in the comparison of CISC vs RISC here - RISC (and 8051) would most likely entail more instructions to code a context switch but does that make it less easy? I could also cloud the issue by talking about PICs - has anyone done a pre-emptive task switcher for them (is it possible??) - maybe on the newer ones. Again, if the context switch and RTOS overhead doesn't impact critically on the application it is not an issue. If the target cpu is an 89C2051 - well I would suggest that using a RTOS is unwise and by using 'c' you're not going to get much functionality - such a task would be best served by carefully crafted assembler. If the target cpu is a derivative with a slab of xram, flash and maybe a 6,2 or 1 clock cpu then what precludes one from using a RTOS if one so desires? Let me re-iterate - I'm not pro RTOS in any instance but the original impetus to my response is Jez suggesting that using a RTOS in a microcontroller is nonsense. I think Donald's response regarding Luddittes is rather apt. |
| Topic | Author | Date |
| RTOS | 01/01/70 00:00 | |
| The typical tradeoffs.... | 01/01/70 00:00 | |
| OS vs. language | 01/01/70 00:00 | |
| os vs language | 01/01/70 00:00 | |
| OS are used at same place where you use | 01/01/70 00:00 | |
| OS and the '51 | 01/01/70 00:00 | |
| OS and the '51 | 01/01/70 00:00 | |
| 511 pages | 01/01/70 00:00 | |
| URL please | 01/01/70 00:00 | |
| web link | 01/01/70 00:00 | |
| web links | 01/01/70 00:00 | |
| NicheTask != Nucleus | 01/01/70 00:00 | |
| Ok why RTOS? | 01/01/70 00:00 | |
| one strange company | 01/01/70 00:00 | |
| No big kernels for little MCUs | 01/01/70 00:00 | |
| thats nice | 01/01/70 00:00 | |
| OS irrelevant | 01/01/70 00:00 | |
| pllease Explain | 01/01/70 00:00 | |
| re pllease Explain | 01/01/70 00:00 | |
| RTOS when? | 01/01/70 00:00 | |
| not when, but how | 01/01/70 00:00 | |
| Job and Tasks | 01/01/70 00:00 | |
| name one | 01/01/70 00:00 | |
| Example | 01/01/70 00:00 | |
| if you need it | 01/01/70 00:00 | |
| Another Example | 01/01/70 00:00 | |
| an example | 01/01/70 00:00 | |
| Problem with Interrupt priorities | 01/01/70 00:00 | |
| Same priority ? | 01/01/70 00:00 | |
| LOOKS LIKE HOMEWORK!!!!!! | 01/01/70 00:00 | |
| RE LOOKS LIKE HOMEWORK!!!!!! | 01/01/70 00:00 | |
| Dont get angry. | 01/01/70 00:00 | |
| On an 8051 | 01/01/70 00:00 | |
| multicoder | 01/01/70 00:00 | |
| quite likely | 01/01/70 00:00 | |
| Pre-emptive multitasking | 01/01/70 00:00 | |
| RTOS-VxWorks | 01/01/70 00:00 | |
| some posts are off-topic | 01/01/70 00:00 | |
| Not very useful | 01/01/70 00:00 | |
| 'C' is not the only language | 01/01/70 00:00 | |
| U cn us RTlinux and VxWorks | 01/01/70 00:00 | |
| RTOS | 01/01/70 00:00 | |
| honesty | 01/01/70 00:00 | |
| 8 bit RToS | 01/01/70 00:00 | |
| How could I have been so wrong! | 01/01/70 00:00 | |
| Perhaps you practice :)) | 01/01/70 00:00 | |
| Well practiced! | 01/01/70 00:00 | |
| Task Switching Overhead | 01/01/70 00:00 | |
| Has the valve been invented yet? | 01/01/70 00:00 | |
| Tunnel vision | 01/01/70 00:00 | |
| because of tunnel vision | 01/01/70 00:00 | |
| Before PCs | 01/01/70 00:00 | |
| fair? | 01/01/70 00:00 | |
| Sure its fair | 01/01/70 00:00 | |
| Show me the apps | 01/01/70 00:00 | |
| Save your appetite | 01/01/70 00:00 | |
| 8051 task switch | 01/01/70 00:00 | |
| Modern derivatives have 4 priority level | 01/01/70 00:00 | |
| Four banks and context switch | 01/01/70 00:00 | |
| anyway | 01/01/70 00:00 | |
| Lemme see..... | 01/01/70 00:00 | |
| So in fact | 01/01/70 00:00 | |
| What is Real Time | 01/01/70 00:00 | |
| real time | 01/01/70 00:00 | |
| Confused | 01/01/70 00:00 | |
| answers | 01/01/70 00:00 | |
| RE: Answers | 01/01/70 00:00 | |
| extern - intern | 01/01/70 00:00 | |
| Agreed | 01/01/70 00:00 | |
| Why not | 01/01/70 00:00 | |
| Give up | 01/01/70 00:00 | |
| Deifinition of a Poor Engineer | 01/01/70 00:00 | |
| so do I | 01/01/70 00:00 | |
| 8051 RTOS Contract | 01/01/70 00:00 | |
| a real speed demon | 01/01/70 00:00 | |
| RTOS/Multitasking discussed so many time | 01/01/70 00:00 | |
Yes | 01/01/70 00:00 |