As discussed in #1341, the current CC13xx/CC26xx IEEE mode driver sends `CMD_GET_RSSI` once and returns the RSSI reading uncondtionally. This happens within the `get_rssi()` function.
This logic is broken if `get_rssi()` is called with the radio off. The function will make sure to turn on the radio first, but it does not make sure the RSSI reading is valid, which only happens a number of symbol periods after the radio enters RX. The outcome is that `NETSTACK_RADIO.get_value(RADIO_PARAM_RSSI, ...)` will always return -128 (meaning that RSSI is unavailable) if the radio was off at the time of calling the function.
The same condition affects the prop mode driver.
This commit changes the logic of `get_rssi()`:
* For PROP mode, if `CMD_GET_RSSI` returns an invalid RSSI, we send it again. For unknown reasons, `CMD_GET_RSSI` on occasion returns 0, so we ignore that value too.
* For IEEE mode, we use `CMD_IEEE_CCA_REQ` and we inspect the value of `ccaInfo.ccaEnergy` of the return structure. If the value is 0x02 (Invalid), we send the command again.
Fixes#1341
Fix for #1229
rf_core_cmd_done_en() was enabling the wrong irq for detecting the
completion of foreground operations. This was causing cc26xx devices
to not wake-up on time when calling lpm_sleep() from transmit().
This commit:
* Moves all cpu files from cpu/cc26xx to cpu/cc26xx-cc13xx
* Bumps the CC26xxware submodule to the latest TI release
* Adds CC13xxware as a submodule
* Adds support for sub-ghz mode / IEEE 802.15.4g
* Splits the driver into multiple files for clarity. We now have the following structure:
* A common module that handles access to the RF core, interrupts etc
* A module that takes care of BLE functionality
* A netstack radio driver for IEEE mode (2.4GHz)
* A netstack radio driver for PROP mode (sub-ghz - multiple bands)
This commit also adds tick suppression functionality, applicable to all chips of the CC26xx and CC13xx families. Instead waking up on every clock tick simply to increment our software counter, we now only wake up just in time to service the next scheduled etimer. ContikiMAC-triggered wakeups are unaffected.
Laslty, this commit also applies a number of minor changes:
* Addition of missing includes
* Removal of stub functions
* Removal of a woraround for a CC26xxware bug that has now been fixed
