Specifications

Performance Metrics
Here are the results of some recent performance measurements, which may help you gauge if SNAPpy
can address your application’s timing requirements.
Time to awaken from sleep (mode 0):
340 ms
Time to awaken from sleep (mode 1):
1.2 ms
Time to startup from power-on:
677 ms
Maximum rate a SNAPpy script can toggle a GPIO pin:
1149.6 Hz
In other words, each True/False cycle took 869.9 µs.
(To change the state of a pin takes 434.9 µs, and each pulse requires two state changes).
Keep in mind that as a general rule, SNAPpy scripts should not be looping, the above rate is only
attainable if the node is doing nothing else (for example, no radio or serial port communication).
Maximum rate for readAdc() calls:
maximum 1107 samples/second. In other words, each sample took 903.1 µs to gather.
NOTE! – This measurement was taken using a script that did not actually do anything with the data.
You will also have to take into consideration any numeric processing required (data thresholding, etc.),
as well as the need to actually store the data someplace.
I
2
C Byte Transfer Time
The actual I
2
C transfers are done using “bit banging” in software. This was measured using a logic
analyzer at 460 µs per byte.
SPI Byte Transfer Time
The actual SPI transfers are done using “bit banging” in software. This was measured using a logic
analyzer at 390 µs per byte.
Virtual Machine Speed
SNAP 2.4 Instructions Per Second (IPS): 3600
Page 172 of 202 SNAP Reference Manual Document Number 600-0007K