BT900-Sx Hardware Integration Guide
Intelligent BTv4.0 Dual Mode Module
Embedded Wireless Solutions Support Center:
http://ews-support.lairdtech.com
www.lairdtech.com/bluetooth
17
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Normal Operation
Min
Typ
Max
Unit
Weak pull-up
-5
-1.0
-0.33
µA
Weak pull-down
0.33
1.0
5.0
µA
CI input capacitance
1.0
-
5.0
pF
This table applies to those BT900 pins ONLY with names beginning with
BT_
:
BT_Ext_DS_CLK (pin 34)
BT_NC (pin 35)
BT_NC (pin 36)
BT_NC (pin 37)
BT_NC (pin 38)
BT_ACTIVE (pin 39)
WLAN_ACTIVE (pin 40)
BT_#SEL (pin 41)
BT_PRIORITY (pin 42)
3.3.3
nAutoRUN pin and Operating Modes
Operating modes (refer to the
smart
BASIC manual for details):
Self-contained mode
Interactive / Development mode
Table 7: nAutoRUN pin
Signal Name
Pin No I/O Comments
nAutoRUN
3
I
Input with active low logic.
Operating mode selected by nAutoRun pin status:
If Low (0V), runs $autorun$ if it exists;
If High (VCC), runs via at+run (and “file name” of application).
Pin 3 (nAutoRUN) is an input, with active low logic. In the development board (DVK-BT900-sx) it is connected
so that the state is driven by the host’s DTR output line. nAutoRUN pin needs to be externally held high or
low to select between the two BT900 operating modes:
Self-contained Run mode (nAutoRUN pin held at 0V).
Interactive / Development mode (nAutoRUN pin held at VCC).
The
smart
BASIC runtime engine firmware checks for the status of nAutoRUN during power-up or reset. If it is
low and if there is a
smart
BASIC application named $autorun$ then the
smart
BASIC runtime engine executes
the application automatically; hence the name
self-contained run mode
.
3.3.4
OTA (Over the Air)
smart
BASIC application download
It is possible to download smart BASIC applications Over the Air (OTA) to the BT900. To enable this, SIO_19
must be pulled low to GND externally (on power up). OTA smartBASIC download is possible from a remote
host when in vSP command mode only.
The OTA
smart
BASIC application download is useful because it allows the module to be soldered into an end
product without pre-configuration; the application can then be downloaded over the air once the product
has been pre-tested. It is the
smart
BASIC application that is downloaded over the air and NOT the firmware.
Since this is primarily meant for production environments with multiple collocated programming stations, the
transmit power is limited.
Table 8: VSP pin description
Signal Name
Pin No I/O Comments
SIO_19
22
I
Internal pull up (default).
