| Re: Speed of SPI Kategorie: Sonstige Hardware (von Torsten - 27.12.2013 11:58) | ||
| Als Antwort auf Speed of SPI von PepeV - 23.12.2013 19:54 | ||
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> Hi all, > > I want to try a new project with my Probot128 to record and play back > sounds. I can record microphone samples with 7200 Hz with ADC in free > running mode. But I cannot store the samples fast enough because there > is only 4 kB SRAM and EEPROM via I2C is too slow. That is why I am > considering extending my robot with extra SRAM via SPI. The question > is, is SPI fast enough? > In assembler surely SPI would be fast enough, but that would probably > be too difficult for me to program. Could someone tell me how fast SPI > is via the byte interpreter commands? How long take SPI_Write() and > SPI_Read()? > > Thanks for any help. > Regards, > Pepe Hallo Pepe, it is a good idea to give the C-Controlsystem more fast memory which we can manage ourselves, and not only for the ProBot128. But I would not recommend to use the functions "SPI_Write(...)" and "SPI_Read(...)" to send several datas. I think it is better to use the function "SPI_WriteBuf(...)". The SPI-interface is also very simple to use in assembler. I did a few measurements with the code below. Look at the file "SPITest-0.01.zip". Using double speed (prescaler = 2) we have: 7.37 Mbit/s SCK cycle = 2 cpu cycles = 136 ns The time to send 20 bytes is whith the: bytecodeinterpreter = ca. 60 µs assembler call = 38.658 µs The time between 2 bytes is by the: bytecodeinterpreter = 20 µs ?;-(|-< assembler version = 1.2 µs These times are only the communication-times without the time for the function calls. Gru� Torsten. SPITest-0.01.zip | ||
Antwort schreiben Antworten:  Re: Speed of SPI (von PepeV - 4.01.2014 17:44) | ||
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