#! /usr/bin/env python3
# Example wiring (LT-8900 on board to Raspberry Pi):
#
# LT-8900
# _--------------------------------------------------------_
# | VCC | RST | MISO | MOSI | SCK | CS | GND |
# |-------+-------+----- -+-------+-------+-------+--------|
# | 3.3v | Reset | SPI | SPI | SPI | SPI | Ground |
# | | | | | Clock | CE0 | |
# -___+___|___+___|___+___|___+___|___+___|___+___|___+____-
# | | | | | | |
# | | | | | | |
# | | | | | | |
# _---+-------+-------+-------+-------+-------+-------+----_
# | 3.3v | GPIO5 | MISO | MOSI | SCLK | CE0 | 0v |
# |-------+-------+-------+-------+-------+-------+--------|
# | P1-17 | P1-18 | P1-21 | P1-19 | P1-23 | P1-24 | P1-25 |
# -________________________________________________________-
# Raspberry Pi
import spidev
import time
class radio:
_register_map = [
{'name': "Unknown"}, # 0
{'name': "Unknown"}, # 1
{'name': "Unknown"}, # 2
{ # 3
'name': 'phase_lock',
'reserved_1': [13, 15],
'rf_synth_lock': [12, 12],
'reserved_2': [0, 11]
},
{'name': "Unknown"}, # 4
{'name': "Unknown"}, # 5
{ # 6
'name': "raw_rssi",
'raw_rssi': [10, 15],
'reserved_1': [0, 9]
},
{ # 7
'name': "radio_state",
'reserved_1': [9, 15],
'tx_enabled': [8, 8],
'rx_enabled': [7, 7],
'channel': [0, 6]
},
{'name': "Unknown"}, # 8
{ # 9
'name': "power",
'current': [12, 15],
'reserved_1': [11, 11],
'gain': [7, 10],
'reserved_2': [0, 6]
},
{ # 10
'name': "gain_block",
'reserved_1': [1, 15],
'enabled': [0, 0]
},
{ # 11
'name': "rssi_power",
'reserved_1': [9, 15],
'mode': [8, 8],
'reserved_2': [0, 7]
},
{'name': "Unknown"}, # 12
{'name': "Unknown"}, # 13
{'name': "Unknown"}, # 14
{'name': "Unknown"}, # 15
{'name': "Unknown"}, # 16
{'name': "Unknown"}, # 17
{'name': "Unknown"}, # 18
{'name': "Unknown"}, # 19
{'name': "Unknown"}, # 20
{'name': "Unknown"}, # 21
{'name': "Unknown"}, # 22
{ # 23
'name': "vco_calibrate",
'reserved_1': [3, 15],
'enabled': [2, 2],
'reserved_2': [0, 1]
},
{'name': "Unknown"}, # 24
{'name': "Unknown"}, # 25
{'name': "Unknown"}, # 26
{ # 27
'name': "crystal",
'reserved_1': [6, 15],
'trim_adjust': [0, 5]
},
{'name': "Unknown"}, # 28
{ # 29
'name': "minor_version",
'reserved_1': [8, 15],
'rf': [4, 7],
'reserved_2': [3, 3],
'digital': [0, 2]
},
{ # 30
'name': "manufacture_1",
'manuf_code_low': [0, 15]
},
{ # 31
'name': "manufacture_2",
'rf_code': [12, 15],
'manuf_code_high': [0, 11]
},
{ # 32
'name': "packet_config",
'preamble_len': [13, 15],
'syncword_len': [11, 12],
'trailer_len': [8, 10],
'packet_type': [6, 7],
'fec_type': [4, 5],
'br_clock_sel': [1, 3],
'reserved_1': [0, 0]
},
{ # 33
'name': "vco_pa_delays",
'vco_on_delay': [8, 15],
'pa_off_delay': [6, 7],
'pa_tx_delay': [0, 5]
},
{ # 34
'name': "tx_packet_delays",
'packet_control_direct': [15, 15],
'tx_cw_delay': [8, 14],
'reserved_1': [6, 7],
'tx_sw_on_delay': [0, 5]
},
{ # 35
'name': "chip_power",
'power_down': [15, 15],
'sleep_mode': [14, 14],
'reserved_1': [13, 13],
'br_clock_on_sleep': [12, 12],
'rexmit_times': [8, 11],
'miso_tri_opt': [7, 7],
'scramble_value': [0, 6]
},
{ # 36
'name': "syncword_0",
'value': [0, 15]
},
{ # 37
'name': "syncword_1",
'value': [0, 15]
},
{ # 38
'name': "syncword_2",
'value': [0, 15]
},
{ # 39
'name': "syncword_3",
'value': [0, 15]
},
{ # 40
'name': "thresholds",
'fifo_empty_threshold': [11, 15],
'fifo_full_threshold': [6, 10],
'syncword_error_bits': [0, 5]
},
{ # 41
'name': "format_config",
'crc_enabled': [15, 15],
'scramble_enabled': [14, 14],
'packet_length_encoded': [13, 13],
'auto_term_tx': [12, 12],
'auto_ack': [11, 11],
'pkt_fifo_polarity': [10, 10],
'reserved_1': [8, 9],
'crc_initial_data': [0, 7]
},
{ # 42
'name': "scan_rssi",
'channel': [10, 15],
'reserved_1': [8, 9],
'ack_time': [0, 7]
},
{ # 43
'name': "scan_rssi_state",
'enabled': [15, 15],
'channel_offset': [8, 14],
'wait_time': [0, 7]
},
{'name': "Unknown"}, # 44
{'name': "Unknown"}, # 45
{'name': "Unknown"}, # 46
{'name': "Unknown"}, # 47
{ # 48
'name': "status",
'crc_error': [15, 15],
'fec_error': [14, 14],
'framer_status': [8, 13],
'syncword_rx': [7, 7],
'packet_flag': [6, 6],
'fifo_flag': [5, 5],
'reserved_1': [0, 4]
},
{'name': "Unknown"}, # 49
{ # 50
'name': "fifo",
'value': [0, 15]
},
{'name': "Unknown"}, # 51
{ # 52
'name': "fifo_state",
'clear_write': [15, 15],
'reserved_1': [14, 14],
'write_ptr': [8, 13],
'clear_read': [7, 7],
'reserved_2': [6, 6],
'read_ptr': [0, 5]
}
]
def __init__(self, spi_bus, spi_dev, config = None):
spi = spidev.SpiDev()
spi.open(spi_bus, spi_dev)
self._spi = spi
self.configure(config)
if len(self._register_map) != 53:
raise ValueError('Inconsistent register map!')
return None
def __del__(self):
self._spi.close()
def _debug(self, message):
#print("LT8900 DEBUG: " + message)
return None
def _reset_device(self):
if self._config is not None:
if self._config['reset_command'] is not None:
return self._config['reset_command']()
return None
def _register_name(self, reg_number):
return self._register_map[reg_number]['name']
def _register_number(self, reg_string):
reg_string_orig = reg_string
if isinstance(reg_string, int):
return reg_string
if reg_string.isnumeric():
return int(reg_string)
for reg_number, reg_info in enumerate(self._register_map):
if reg_info['name'] == reg_string:
return reg_number
raise NameError("Invalid register value {}".format(reg_string_orig))
def _check_radio(self):
value1 = self.get_register(0);
value2 = self.get_register(1);
if value1 == 0x6fe0 and value2 == 0x5681:
return True
return False
def _set_defaults(self):
self.put_register_bits('radio_state', {'tx_enabled': 0, 'rx_enabled': 0, 'channel': 76})
self.put_register_bits('power', {'current': 4, 'gain': 0})
self.put_register_bits('rssi_power', {'mode': 0})
self.put_register_bits('crystal', {'trim_adjust': 0})
self.put_register_bits('packet_config', {
'preamble_len': 2,
'syncword_len': 1,
'trailer_len': 0,
'packet_type': 0,
'fec_type': 0,
'br_clock_sel': 0
})
self.put_register_bits('chip_power', {
'power_down': 0,
'sleep_mode': 0,
'br_clock_on_sleep': 0,
'rexmit_times': 3,
'miso_tri_opt': 0,
'scramble_value': 0
})
self.put_register_bits('thresholds', {
'fifo_empty_threshold': 8,
'fifo_full_threshold': 16,
'syncword_error_bits': 2
})
self.put_register_bits('format_config', {
'crc_enabled': 1,
'scramble_enabled': 0,
'packet_length_encoded': 1,
'auto_term_tx': 1,
'auto_ack': 0,
'pkt_fifo_polarity': 0,
'crc_initial_data': 0
})
self.put_register_bits('scan_rssi', {'channel': 63, 'ack_time': 176})
self.put_register_bits('gain_block', {'enabled': 1})
self.put_register_bits('vco_calibrate', {'enabled': 1})
self.put_register_bits('scan_rssi_state', {'enabled': 0, 'channel_offset': 0, 'wait_time': 15})
return True
def _put_register_high_low(self, reg, high, low, delay = 7):
reg = self._register_number(reg)
result = self._spi.xfer([reg, high, low], self._spi.max_speed_hz, delay)
if reg & 0x80 == 0x80:
self._debug(" regRead[%02X] = %s" % ((reg & 0x7f), result))
else:
self._debug("regWrite[%02X:0x%02X%02X] = %s" % (reg, high, low, result))
return result
def put_register(self, reg, value):
high = (value >> 8) & 0xff
low = value & 0xff
return self._put_register_high_low(reg, high, low)
def put_register_bits(self, reg, bits_dict):
# Convert register to an integer
reg = self._register_number(reg)
# Lookup register in the register map
register_info = self._register_map[reg]
# Create a dictionary to hold the parsed results
value = 0
for key in bits_dict:
if key == "name":
continue
bit_range = register_info[key]
mask = ((1 << (bit_range[1] - bit_range[0] + 1)) - 1) << bit_range[0]
key_value = (bits_dict[key] << bit_range[0]) & mask
value = value | key_value
result = self.put_register(reg, value)
return result
def get_register(self, reg):
# Convert register to an integer
reg = self._register_number(reg)
# Reading of a register is indicated by setting high bit
read_reg = reg | 0b10000000
# Put the request with space for the reply
value = self._put_register_high_low(read_reg, 0, 0)
# The reply is stored in the lower two bytes
result = value[1] << 8 | value[2]
# Return result
return result
def get_register_bits(self, reg, value = None):
# Convert register to an integer
reg = self._register_number(reg)
# Get the register's value (unless one was supplied)
if value is None:
value = self.get_register(reg)
# Lookup register in the register map
register_info = self._register_map[reg]
# Create a dictionary to hold the parsed results
result = {'name': register_info['name']}
for key in register_info:
if key == "name":
continue
bit_range = register_info[key]
mask = ((1 << (bit_range[1] - bit_range[0] + 1)) - 1) << bit_range[0]
key_value = (value & mask) >> bit_range[0]
result[key] = key_value
# Return the filled in structure
return result
def configure(self, config):
self._config = config
if config is None:
return None
self._spi.max_speed_hz = self._config.get('frequency', 4000000)
self._spi.bits_per_word = self._config.get('bits_per_word', 8)
self._spi.cshigh = self._config.get('csigh', False)
self._spi.no_cs = self._config.get('no_cs', False)
self._spi.lsbfirst = self._config.get('lsbfirst', False)
self._spi.threewire = self._config.get('threewire', False)
self._spi.mode = self._config.get('mode', 1)
return None
def initialize(self):
self._reset_device()
self._set_defaults()
if not self._check_radio():
return False
return True
def set_channel(self, channel):
state = self.get_register_bits('radio_state')
state['channel'] = channel
self.put_register_bits('radio_state', state)
return state
def set_syncword(self, syncword):
packet_config = self.get_register_bits('packet_config')
packet_config['syncword_len'] = len(syncword) - 1
self.put_register_bits('packet_config', packet_config)
if len(syncword) == 1:
self.put_register("syncword_0", syncword[0])
elif len(syncword) == 2:
self.put_register("syncword_0", syncword[1])
self.put_register("syncword_3", syncword[0])
elif len(syncword) == 3:
self.put_register("syncword_0", syncword[2])
self.put_register("syncword_2", syncword[1])
self.put_register("syncword_3", syncword[0])
elif len(syncword) == 4:
self.put_register("syncword_0", syncword[3])
self.put_register("syncword_1", syncword[2])
self.put_register("syncword_2", syncword[1])
self.put_register("syncword_3", syncword[0])
elif len(syncword) > 4:
raise ValueError("SyncWord length must be less than 5")
return None
def fill_fifo(self, message, include_length = True):
new_message = [self._register_number('fifo')]
if include_length:
new_message = new_message + [len(message)]
new_message = new_message + message
log_message = [] + new_message
# Transfer the message
result = self._spi.xfer(new_message, self._spi.max_speed_hz, 10)
self._debug("Writing: {} = {}".format(log_message, result))
return new_message
def transmit(self, message, channel = None):
if channel is None:
state = self.get_register_bits('radio_state')
channel = state['channel']
# Initialize the transmitter
self.put_register_bits('radio_state', {
'tx_enabled': 0,
'rx_enabled': 0,
'channel': 0
})
self.put_register_bits('fifo_state', {
'clear_read': 1,
'clear_write': 1
})
# Format message to send to fifo
self.fill_fifo(message, True)
# Tell the radio to transmit the FIFO buffer to the specified channel
self.put_register_bits('radio_state', {
'tx_enabled': 1,
'rx_enabled': 0,
'channel': channel
})
# Wait for buffer to empty
# XXX: Untested
while True:
radio_status = self.get_register_bits('status')
self._debug("radio_status={}".format(radio_status))
if radio_status['packet_flag'] == 1:
break
time.sleep(0.001)
return True
def multi_transmit(self, message, channels, retries = 3, delay = 0.1):
for channel in channels:
for i in range(retries):
if not self.transmit(message, channel):
return False
if delay != 0:
time.sleep(delay / retries)
return True
def start_listening(self, channel):
# Initialize the receiver
self.stop_listening()
# Go into listening mode
self.put_register_bits('radio_state', {
'tx_enabled': 0,
'rx_enabled': 1,
'channel': channel
})
return True
def stop_listening(self):
# Initialize the receiver
self.put_register_bits('radio_state', {
'tx_enabled': 0,
'rx_enabled': 0,
'channel': 0
})
self.put_register_bits('fifo_state', {
'clear_read': 1,
'clear_write': 1
})
return True
def receive(self, channel = None, wait = False, length = None, wait_time = 0.1):
if wait:
if channel is None:
state = self.get_register_bits('radio_state')
channel = state['channel']
self.start_listening(channel)
message = []
while True:
radio_status = self.get_register_bits('status')
if radio_status['packet_flag'] == 0:
if wait:
time.sleep(wait_time)
continue
else:
return None
if radio_status['crc_error'] == 1:
# Handle invalid packet ?
self.start_listening(channel)
continue
# Data is available, read it from the FIFO register
# The first result will include the length
# XXX *IF* length encoding is enabled ?
fifo_data = self.get_register('fifo')
message_length = fifo_data >> 8
# Keep track of the total message length to truncate it
final_message_length = message_length
message += [fifo_data & 0xff]
message_length -= 1
# Read subsequent bytes from the FIFO register until
# there are no more bytes to read
while message_length > 0:
fifo_data = self.get_register('fifo')
message += [fifo_data >> 8, fifo_data & 0xff]
message_length -= 2
# Truncate the message to its final size, since we have
# to read in 16-bit words, we may have an extra byte
message = message[0:final_message_length]
break
return message