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manual: adapt to LED on RTIO

This commit is contained in:
Sebastien Bourdeauducq 2015-04-17 10:43:50 +08:00
parent 52fe66ee4d
commit c1ece33e6d
1 changed files with 6 additions and 4 deletions
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10
doc/manual/getting_started.rst
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@ -46,11 +46,14 @@ Modify the code as follows: ::
@kernel @kernel
def run(self): def run(self):
if input_led_state(): s = input_led_state()
self.core.recover_underflow()
if s:
self.led.on() self.led.on()
else: else:
self.led.off() self.led.off()
You can then turn the LED off and on by entering 0 or 1 at the prompt that appears: :: You can then turn the LED off and on by entering 0 or 1 at the prompt that appears: ::
$ artiq_run.py led.py $ artiq_run.py led.py
@ -60,6 +63,8 @@ You can then turn the LED off and on by entering 0 or 1 at the prompt that appea
What happens is the ARTIQ compiler notices that the ``input_led_state`` function does not have a ``@kernel`` decorator and thus must be executed on the host. When the core device calls it, it sends a request to the host to execute it. The host displays the prompt, collects user input, and sends the result back to the core device, which sets the LED state accordingly. What happens is the ARTIQ compiler notices that the ``input_led_state`` function does not have a ``@kernel`` decorator and thus must be executed on the host. When the core device calls it, it sends a request to the host to execute it. The host displays the prompt, collects user input, and sends the result back to the core device, which sets the LED state accordingly.
The ``recover_underflow`` call is necessary to waive the real-time requirements of the LED state change (as the ``input_led_state`` function can take an arbitrarily long time). This will become clearer later as we explain timing control.
Algorithmic features Algorithmic features
-------------------- --------------------
@ -109,18 +114,15 @@ Try reducing the period of the generated waveform until the CPU cannot keep up w
class Tutorial(Experiment, AutoDB): class Tutorial(Experiment, AutoDB):
class DBKeys: class DBKeys:
core = Device() core = Device()
led = Device()
ttl0 = Device() ttl0 = Device()
@kernel @kernel
def run(self): def run(self):
self.led.off()
try: try:
for i in range(1000000): for i in range(1000000):
self.ttl0.pulse(...) self.ttl0.pulse(...)
delay(...) delay(...)
except RTIOUnderflow: except RTIOUnderflow:
self.led.on()
print_underflow() print_underflow()
Parallel and sequential blocks Parallel and sequential blocks