When the clock is too fast for the i2c slave, it can temporarily hold
down the scl line to signal to the master that it needs to wait. The
master should check the scl line when it is releasing it after
transmitting data, and wait for it to be released.
This change has been tested with a logic analyzer and an i2c slace
implemented on an atmega328p using its twi peripheral, clocked at 8Mhz.
Without the change, the i2c communication works up to aboy 150kHz
frequency, and above that results in the slave stuck in an unresponsive
state. With this change, communication has been tested to work up to
400kHz.
Adds horizontal scrolling. Right now, I'm just leaving the margins
created by the scrolling as they were -- so they will repeat the
edge of the framebuf. This is fast, and the user can always fill
the margins themselves.
There was a bug in `framebuf1_fill` function, that makes it leave a few
lines unfilled at the bottom if the height is not divisible by 8.
A similar bug is fixed in the scroll method.
The idea is that all ports can use these helper methods and only need to
provide initialisation of the SPI bus, as well as a single transfer
function. The coding pattern follows the stream protocol and helper
methods.
This is an object-oriented approach, where uos is only a proxy for the
methods on the vfs object. Some internals had to be exposed (the STATIC
keyword removed) for this to work.
Fixes#2338.
In `btree_seq()`, when `__bt_seq()` gets called with invalid
`flags` argument it will return `RET_ERROR` and it won't
initialize `val`. If field `data` of uninitialized `val`
is passed to `mp_obj_new_bytes()` it causes a segfault.
Alex March
Paul Sokolovsky
Radomir Dopieralski
Pavol Rusnak
Stefan Agner
Damien George
Krzysztof Blazewicz