4.3. Power up
Set and hold the
pin to LOW. After the supply voltage to the module has stabilized,
the
pin shall be held LOW level for another
∆
t of at least 200 ms to ensure a safe
start-up. Before releasing the
pin, make sure that the appropriate voltage levels are
applied on pins
and
according to the desired application mode
(see
). Also make sure that the host’s UART TX line to the module is configured as a
logic HIGH level during module boot-up. The module will send a Start-up UART message
once it has booted and started the application.
For further timing information refer chapter
. If the module is used on a battery-powered
system, using a suitable reset-IC (or a discrete RC block for a delay) is highly recommended
to ensure a correct power up and stable behavior independent of battery status.
The typical time for
∆
t is in the order of 1 second. An additional 1.1 seconds (typical) delay
is introduced on first boot due to extended calibration (e.g. after a firmware update). Upon
hard-reset the firmware integrity check will add further latency into t_boot.
Figure 3: Power up
4.4. Region specific WLAN settings
Despite the world-wide availability of the 2.4 GHz frequency band, there are region specific
restrictions on availability of certain channels. In order to be complaint with local regulations,
the country code on the module has to be set-up before deployment. By default the country
code is set to "US". Country code can be changed by sending the following command to the
module. Refer to section
for more details. On request, the modules can be produced
with the application-specific country code (see chapter
).
AT+ w l a n s e t = g e n e r a l , country_code , EU
OK
Calypso reference manual version 1.2
© April 2019
www.we-online.com/wireless-connectivity
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