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Diffstat (limited to 'spi/nrf24l01/README')
| -rw-r--r-- | spi/nrf24l01/README | 109 |
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diff --git a/spi/nrf24l01/README b/spi/nrf24l01/README new file mode 100644 index 0000000..0d7667c --- /dev/null +++ b/spi/nrf24l01/README @@ -0,0 +1,109 @@ +------------------------------------------------------------------------------- +nRF24L01/nRF24L01+ +------------------------------------------------------------------------------- + +This directory contains a capture of the communication between two nRF24L01+ +tranceivers, one connected to a Raspberry Pi and the other connected to an +AVR microcontroller, and some generated files to test paths in the protocol +decoder that aren't covered in the capture. + + +nrf24l01-communication.sr +------------------------- + +Logic analyzer setup +-------------------- + +The logic analyzer used was a Lcsoft Mini Board (at 12MHz): + + Probe Description + --------------------------- + PB0 (TRG) used to trigger the logic analyzer + PB1 (rpi_CSN) chip select signal of the receiving chip, active low + PB2 (rpi_CLK) clock signal of the receiving chip + PB3 (rpi_MOSI) MOSI signal of the receiving chip + PB4 (rpi_MISO) MISO signal of the receiving chip + PB5 (rpi_IRQ) interrupt signal fo the receiving chip, active low + PD0 (uc_CSN) chip select signal of the sending chip, active low + PD1 (uc_CLK) clock signal of the sending chip + PD2 (uc_MOSI) MOSI signal of the sending chip + PD3 (uc_MISO) MISO signal of the sending chip + + Note that the nRF24L01(+) chips have two chip select pins, "CE" used to + control the standby mode, and "CSN" used for SPI communication. This capture + only contains the "CSN" signals of the two chips. + +Data +---- + +The sigrok command line used was: + + sigrok-cli --driver fx2lafw --config samplerate=12M \ + -p '0=TRG,1=rpi_CSN,2=rpi_CLK,3=rpi_MOSI,4=rpi_MISO,5=rpi_IRQ,8=uc_CSN,9=uc_CLK,10=uc_MOSI,11=uc_MISO' \ + -t TRG=0 --time 140 -o nrf24l01-communication.sr + +The capture starts with the Raspberry Pi initializing its chip as a receiver, +followed by the microcontroller initializing the second chip as a transmitter +at about 8.8ms - 9ms. 30ms after the start of the capture, the microcontroller +starts sending the strings "message #0" to "message #9" in intervalls of about +10ms. After sending a message, it uses polling to detect when the message is +sent and the acknowledge from the receiver is received. The Raspberry Pi handles +the first six messages after the receiving chip asserts the interrupt signal. +Because it doesn't handle the other four messages and the receive fifo in the +receiver runs full after three messages, the last message isn't acknowledged. +The sender detects that and reads the lost packet counter from the sender chip, +which consequently has a value of one. + + +nrf24l01-communication-[rx|tx].sr +---------------------------- + +These files were generated from the file 'nrf24l01-communication.sr' using +the commands + + sigrok-cli -i nrf24l01-communication.sr -O csv | \ + awk -F , '{if (NR > 3) {print $2","$3","$4","$5}}' | \ + sigrok-cli -i /dev/fd/0 -I csv:samplerate=12M -o nrf24l01-communication-rx.sr + +and + + sigrok-cli -i nrf24l01-communication.sr -O csv | \ + awk -F , '{if (NR > 3) {print $7","$8","$9","$10}}' | \ + sigrok-cli -i /dev/fd/0 -I csv:samplerate=12M -o nrf24l01-communication-tx.sr + +respectively, because apparently the pdtest/runtc tools don't support capture +files with extra channels. The files are then used to check if the protocol +decoder correctly decodes the message payload. + + +nrf24l01-test-... +-------------------- + +These files were generated by the 'gen-testfiles.py' script and contain test +cases for the decoder that aren't yet covered by the other captures. + + ...-activate.sr: Tests decoding of the 'ACTIVATE' instruction. This + instruction is only valid for the nRF24L01 chips + (without the plus) and is therefore not in the + communication dump. + + ...-excess-bytes.sr: Used to check if the protocol decoder correctly + recognizes and reports superfluous bytes after the + commands. + + ...-misc.sr: Contains checks for the instructions 'REUSE_TX_PL', + 'R_RX_PL_WID', and 'W_ACK_PAYLOAD', that aren't + covered by the other dumps. + + ...-missing-bytes.sr: Used to check if the protocol decoder correctly + recognizes and reports missing bytes after the + commands. + + ...-no-command.sr: Used to check if the protocol decoder correctly + handles empty commands. + + ...-unknown-command.sr: Used to check if the protocol decoder correctly + recognizes commands that do not exist. + + ...-unknown-register.sr: Contains a 'R_REGISTER' (read register) instruction + of a non-existing register. |