8 This driver is for controlling pi433, a radio module for the Raspberry Pi
9 (www.pi433.de). It supports transmission and reception. It can be opened
10 by multiple applications for transmission and reception. While transmit
11 jobs were queued and process automatically in the background, the first
12 application asking for reception will block out all other applications
13 until something gets received terminates the read request.
14 The driver supports on the fly reloading of the hardware fifo of the rf
15 chip, thus enabling for much longer telegrams then hardware fifo size.
17 Discription of driver operation
18 ===============================
22 Each transmission can take place with a different configuration of the rf
23 module. Therefore each application can set its own set of parameters. The driver
24 takes care, that each transmission takes place with the parameterset of the
25 application, that requests the transmission. To allow the transmission to take
26 place in the background, a tx thread is introduced.
27 The transfer of data from the main thread to the tx thread is realised by a
28 kfifo. With each write request of an application, the passed in data and the
29 corresponding parameter set gets written to the kfifo.
30 On the other "side" of the kfifo, the tx thread continuously checks, whether the
31 kfifo is empty. If not, it gets one set of config and data from the kfifo. If
32 there is no receive request or the receiver is still waiting for something in
33 the air, the rf module is set to standby, the parameters for transmission gets
34 set, the hardware fifo of the rf chip gets preloaded and the transmission gets
35 started. Upon hardware fifo threshold interrupt it gets reloaded, thus enabling
36 much longer telegrams than the hardware fifo size. If the telegram is sent and there
37 is more data available in the kfifo, the procedure is repeated. If not the
38 transmission cycle ends.
42 Since there is only one application allowed to receive data at a time, for
43 reception there is only one configuration set.
44 As soon as an application sets a request for receiving a telegram, the reception
45 configuration set is written to the rf module and it gets set into receiving mode.
46 Now the driver is waiting, that a predefined RSSI level (signal strength at the
47 receiver) is reached. Until this hasn't happened, the reception can be
48 interrupted by the transmission thread at any time to insert a transmission cycle.
49 As soon as the predefined RSSI level is meat, a receiving cycle starts. Similar
50 as described for the transmission cycle the read out of the hardware fifo is done
51 dynamically. Upon each hardware fifo threshold interrupt, a portion of data gets
52 read. So also for reception it is possible to receive more data then the hardware
59 The driver is currently implemented as a character device. Therefore it supports
60 the calls open, ioctl, read, write and close.
66 There are four options:
67 PI433_IOC_RD_TX_CFG - get the transmission parameters from the driver
68 PI433_IOC_WR_TX_CFG - set the transmission parameters
69 PI433_IOC_RD_RX_CFG - get the receiving parameters from the driver
70 PI433_IOC_WR_RX_CFG - set the receiving parameters
72 The tx configuration is transferred via struct pi433_tx_cfg, the parameterset for transmission.
73 It is divided into two sections: rf parameters and packet format.
77 frequency used for transmission.
78 Allowed values: 433050000...434790000
80 bit rate used for transmission.
83 frequency deviation in case of FSK.
84 Allowed values: 600...500000
86 FSK - frequency shift key
89 shapingOff - no shaping
90 shaping1_0 - gauss filter with BT 1 (FSK only)
91 shaping0_5 - gauss filter with BT 0.5 (FSK only)
92 shaping0_3 - gauss filter with BT 0.3 (FSK only)
93 shapingBR - filter cut off at BR (OOK only)
94 shaping2BR - filter cut off at 2*BR (OOK only)
96 ramp3400 - amp ramps up in 3.4ms
97 ramp2000 - amp ramps up in 2.0ms
98 ramp1000 - amp ramps up in 1ms
99 ramp500 - amp ramps up in 500us
100 ramp250 - amp ramps up in 250us
101 ramp125 - amp ramps up in 125us
102 ramp100 - amp ramps up in 100us
103 ramp62 - amp ramps up in 62us
104 ramp50 - amp ramps up in 50us
105 ramp40 - amp ramps up in 40us
106 ramp31 - amp ramps up in 31us
107 ramp25 - amp ramps up in 25us
108 ramp20 - amp ramps up in 20us
109 ramp15 - amp ramps up in 15us
110 ramp12 - amp ramps up in 12us
111 ramp10 - amp ramps up in 10us
113 fifo_level - transmission starts, if fifo is filled to
115 fifo_not_empty - transmission starts, as soon as there is one
116 byte in internal fifo
118 This gives the option, to send a telegram multiple times. Default: 1
122 optionOn - a preamble will be automatically generated
123 optionOff - no preamble will be generated
125 optionOn - a sync word will be automatically added to
126 the telegram after the preamble
127 optionOff - no sync word will be added
128 Attention: While possible to generate sync without preamble, the
129 receiver won't be able to detect the sync without preamble.
131 optionOn - the length of the telegram will be automatically
132 added to the telegram. It's part of the payload
133 optionOff - no length information will be automatically added
135 Attention: For telegram length over 255 bytes, this option can't be used
136 Attention: should be used in combination with sync, only
138 optionOn - the address byte will be automatically added to the
139 telegram. It's part of the payload
140 optionOff - the address byte will not be added to the telegram.
141 The address byte can be used for address filtering, so the receiver
142 will only receive telegrams with a given address byte.
143 Attention: should be used in combination with sync, only
145 optionOn - an crc will be automatically calculated over the
146 payload of the telegram and added to the telegram
148 optionOff - no crc will be calculated
150 length of the preamble. Allowed values: 0...65536
152 length of the sync word. Allowed values: 0...8
154 length of the payload of the telegram. Will override the length
155 given by the buffer, passed in with the write command. Will be
156 ignored if set to zero.
158 contains up to eight values, that are used as the sync pattern
161 one byte, used as address byte on address byte option.
164 The rx configuration is transferred via struct pi433_rx_cfg, the parameterset for receiving. It is divided into two sections: rf parameters and packet format.
168 frequency used for transmission.
169 Allowed values: 433050000...434790000
171 bit rate used for transmission.
172 Allowed values: #####
174 frequency deviation in case of FSK.
175 Allowed values: 600...500000
177 FSK - frequency shift key
180 threshold value for the signal strength on the receiver input.
181 If this value is exceeded, a reception cycle starts
182 Allowed values: 0...255
184 in order to adapt to different levels of singnal strength, over
185 time the receiver gets more and more sensitive. This value
186 determs, how fast the sensitivity increases.
187 step_0_5db - increase in 0,5dB steps
188 step_1_0db - increase in 1 db steps
189 step_1_5db - increase in 1,5dB steps
190 step_2_0db - increase in 2 db steps
191 step_3_0db - increase in 3 db steps
192 step_4_0db - increase in 4 db steps
193 step_5_0db - increase in 5 db steps
194 step_6_0db - increase in 6 db steps
196 sets the electrical adoption of the antenna
197 fifty_ohm - for antennas with an impedance of 50Ohm
198 two_hundred_ohm - for antennas with an impedance of 200Ohm
200 sets the gain of the low noise amp
201 automatic - lna gain is determined by an agc
202 max - lna gain is set to maximum
203 max_minus_6 - lna gain is set to 6db below max
204 max_minus_12 - lna gain is set to 12db below max
205 max_minus_24 - lna gain is set to 24db below max
206 max_minus_36 - lna gain is set to 36db below max
207 max_minus_48 - lna gain is set to 48db below max
209 sets the bandwidth of the channel filter - part one: mantisse.
210 mantisse16 - mantisse is set to 16
211 mantisse20 - mantisse is set to 20
212 mantisse24 - mantisse is set to 24
214 sets the bandwidth of the channel filter - part two: exponent.
217 operation mode of the digital automatic gain control
220 improve_for_low_modulation_index
224 optionOn - sync detection is enabled. If configured sync pattern
225 isn't found, telegram will be internally discarded
226 optionOff - sync detection is disabled.
228 optionOn - First byte of payload will be used as length byte,
229 regardless of the amount of bytes that were requested
231 optionOff - Number of bytes to be read will be set according to
232 amount of bytes that were requested by the read request.
233 Attention: should be used in combination with sync, only
234 enable_address_filtering;
235 filtering_off - no address filtering will take place
236 node_address - all telegrams, not matching the node
237 address will be internally discarded
238 node_or_broadcast_address - all telegrams, neither matching the
239 node, nor the broadcast address will
240 be internally discarded
241 Attention: Sync option must be enabled in order to use this feature
243 optionOn - a crc will be calculated over the payload of
244 the telegram, that was received. If the
245 calculated crc doesn't match to two bytes,
246 that follow the payload, the telegram will be
247 internally discarded.
248 Attention: This option is only operational if sync on and fixed length
249 or length byte is used
251 Gives the length of the payload.
252 Attention: This setting must meet the setting of the transmitter,
253 if sync option is used.
255 Overrides the telegram length either given by the first byte of
256 payload or by the read request.
258 gives the number of bytes, that will be dropped before transferring
259 data to the read buffer
260 This option is only useful if all packet helper are switched
261 off and the rf chip is used in raw receiving mode. This may be
262 needed, if a telegram of a third party device should be received,
263 using a protocol not compatible with the packet engine of the rf69 chip.
265 contains up to eight values, that are used as the sync pattern
267 This setting must meet the configuration of the transmitting device,
268 if sync option is enabled.
270 one byte, used as node address byte on address byte option.
272 one byte, used as broadcast address byte on address byte option.