This allows switching back and forth between 10 and 11 bit
code which prevents getting locked up in one or the other.
It also avoids a situation that can cause an infinite
recursion.
This changeset is cherry-picked from TauLabs (b7eaf87502085666d9738ae16c66170f187f3981).
Thanks to Taulabs for improving OpenPilot's DSM autodetect feature.
- performs undersampling in two steps operating with a half buffer at time;
- Skip costly undersampling for Temperature channel;
- some optimizations to the downsample loops;
- apply compiler speed optimization to PIOS_ADC_downsample_data()
Moves the CMSIS system_stm3210x.c from library.mk to the individual Makefiles for the F1 targets. This allows for custom SystemInit functions where necessary.
USB CDC uses BULK endpoints to send/receive data. Typically,
a USB host will enqueue large buffers on its IN (device-to-host)
URBs. These buffers are larger than the max packet size for the
bulk endpoint.
The USB standard requires that an IN transfer ends when one of
these is true:
* a short packet (ie. less than max packet size) is sent by the
device
* a zero length packet (ZLP)
* enough packets that the entire host buffer is filled
Our device implementation never sends ZLPs. We sometimes send
packets that are exactly max-packet-size bytes long. This would
result in partially filling a host buffer without signalling (via
ZLP) that the transmission had finished. The host would then wait
until the next transfer had taken place before processing the first
data, thus delaying the first data.
This change simply forces all of our transfers to be short packets
and avoids the need to worry about zero length packets. This is
at the cost of some efficiency on the host side since its large
buffers will only ever be partially filled.
Conflicts:
flight/PiOS/STM32F30x/pios_usb_cdc.c
CDC and USART device drivers were not all clearing their
device structs before using them.
This specifically caused crashes in the case where the upper
COM layer was binding only a Tx path. The Rx path callback
in the lower driver was uninitialized random data and would
result in the lower driver faulting when it tried to call the
callback.
Conflicts:
flight/PiOS/STM32F30x/pios_usart.c
flight/PiOS/STM32F30x/pios_usb_cdc.c
flight/PiOS/STM32F30x/pios_usb_hid.c
