When an IRQ is lost during cc110x_send(), the driver will remain locked until
another IRQ is triggered. This commit changes the behavior to wait for at most
an reasonable upper bound, which is chosen to not only allow the driver to
recover but also (at least in theory) complete the transmission correctly.
This (re-)introduces the `CC110X_DEFAULT_CHANNEL` preprocessor macro to set the
default channel of the `cc110x` at compile time. The same macro has been used
in the previous version of the driver, so some users might still expect it to
work.
The cc110x driver has been re-written from scratch to overcome the limitations
of the old driver. The main motivation of the rewrite was to achieve better
maintainability by a detailed documentation, reduce the complexity and the
overhead of the SPI communication with the device, and to allow to
simultaneously use transceivers with different configuration regarding the used
base band, the channel bandwidth, the modulation rate, and the channel map.
Features of this driver include:
- Support for the CC1100, CC1101, and the CC1100e sub-gigahertz transceivers.
- Detailed documentation of every aspect of this driver.
- An easy to use configuration API that allows setting the transceiver
configuration (modulation rate, channel bandwidth, base frequency) and the
channel map.
- Fast channel hopping by pre-calibration of the channels during device
configuration (so that no calibration is needed during hopping).
- Simplified SPI communication: Only during start-up the MCU has to wait
for the transceiver to be ready (for the power regulators and the crystal
to stabilize). The old driver did this for every SPI transfer, which
resulted in complex communication code. This driver will wait on start up
for the transceiver to power up and then use RIOT's SPI API like every other
driver. (Not only the data sheet states that this is fine, it also proved to
be reliable in practise.)
- Greatly reduced latency: The RTT on the old driver (@150 kbps data rate) was
about 16ms, the new driver (@250 kbps data rate) has as RTT of ~3ms
(depending on SPI clock and on CPU performance) (measured with ping6).
- Increased reliability: The preamble size and the sync word size have been
doubled compared to the old driver (preamble: 8 bytes instead of 4,
sync word: 4 byte instead of 2). The new values are the once recommended by
the data sheet for reliable communication.
- Basic diagnostic during driver initialization to detect common issues as
SPI communication issues and GDO pin configuration/wiring issues.
- TX power configuration with netdev_driver_t::set() API-integration
- Calls to netdev_driver_t::send() block until the transmission has completed
to ease the use of the API (implemented without busy waiting, so that the
MCU can enter lower power states or other threads can be executed).
