User's Manual

Table Of Contents
BlueMod+S42 Hardware User Guide
1VV0301303 Rev.32016-08-22
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 29 of 62
C
L
= (C1+C
pin
+C
s
) * (C2+C
pin
+C
s
) / (C1+C2+2*C
pin
+2*Cs), or
C1, C2 = (2*C
L
– C
pin
– C
s
)
C
pin
: see Table 5
C
s
: stray capacitance, depends on layout
Figure 11: BlueMod+S42 connection of external XTAL
3.10 Test Mode
For homologation purposes the ability of test mode operation like “BlueMod+S42_Testmode
or “Direct two wire UART Testmode” (DTM) is mandatory. The Direct Test Mode (as
defined by the Bluetooth SIG) and BlueMod+S42_Testmode are part of the BlueMod+S42
TIO-Firmware. Please refer to tbd.
For enabling the different test modes the BlueMod+S42 provides two IO pins.
The pin Testmode is low active. Active in the following table means connect to GND.
The pin Boot0 is high active. Active in the following table means connect to VDD.
The other two combinations start the bootloader for firmware update of the
programmed firmware. These two modes are not scope of this document.
Table 6 shows the possible combinations:
Testmode#
Boot0
Mode
Active Inactive Testmode
Active Active DTM
Inactive Active Start Bootloader
Inactive Inactive Firmware Update
Table 6: Testmode# / Boot0 Logic
XL-IN
BlueMod+S42
A-6
Slow Clock
XL-OUT
A-5
32,768kHz
CL: 9pF
C1
C2
C1, C2 ~ 12pF