| ??? 08/08/10 14:03 Read: times |
#177879 - Pardon accepted Responding to: ???'s previous message |
Andy Neil said:
Johan Smit said:
Call send_char from inside the serial interrupt. While in send_char do a reti. Then the interrupts are free, and you stay in send_char. Eh??? If you do a RETI, it will cause a return, so you will not still be in send_char - surely?! Then, when you hit the RETI at the end of the ISR, the fun really starts... Let's look at the stack pointer. In main routine SP = x Serial interrupt occurs In serial interrupt handler SP = x+2 Call send_char In send_char SP = x=4 Call free_int In free_int SP = x+6 Reti SP = x+4 Ret at end of free_int SP = x+2 In send_char SP = x+2 Return from send_char SP = x You are in main routine The reti is necessary for the hardware to reset and enable the next interrupt. It was not me that was so clever. The principle is used in the Quantum Leaps RTOS. Regards Johan Smit |
| Topic | Author | Date |
| Writing to SBUF in Serial Routine | 01/01/70 00:00 | |
| Sure... | 01/01/70 00:00 | |
| yes, but | 01/01/70 00:00 | |
| TX inside serialint | 01/01/70 00:00 | |
| Pardon?? | 01/01/70 00:00 | |
| Pardon accepted | 01/01/70 00:00 | |
| Still a Missing Part of Scheme | 01/01/70 00:00 | |
| Pardon | 01/01/70 00:00 | |
| Will that work in 'C' ? | 01/01/70 00:00 | |
| Assembler if you want | 01/01/70 00:00 | |
| Why send_char? | 01/01/70 00:00 | |
| Why send_char | 01/01/70 00:00 | |
| You missed the point | 01/01/70 00:00 | |
| Call a routine from an interrupt | 01/01/70 00:00 | |
| Still misunderstanding | 01/01/70 00:00 | |
misunderstandings | 01/01/70 00:00 | |
| what happened to the OP? | 01/01/70 00:00 |