User Guide
Table Of Contents
- Document information
- Contents
- 1 LARA-R2 / LARA-R6 modules description
- 2 Migration between LARA modules
- 2.1 Overview
- 2.2 Pin-out comparison between LARA modules
- 2.3 Interfaces comparison between LARA modules
- 2.3.1 VCC module supply input
- 2.3.2 V_INT 1.8 V supply output
- 2.3.3 V_BCKP RTC supply input/output
- 2.3.4 Cellular RF interfaces
- 2.3.5 System control interfaces
- 2.3.6 SIM interface
- 2.3.7 UART interfaces
- 2.3.8 USB interface
- 2.3.9 I2C interface
- 2.3.10 Digital audio interface
- 2.3.11 Clock output
- 2.3.12 GPIOs
- 2.3.13 Antenna dynamic tuning
- 2.3.14 Reserved pins
- 2.3.15 Other considerations and test points
- 2.4 Schematic for LARA modules integration
- Appendix
- A Glossary
- Related documents
- Revision history
- Contact
LARA-R2/R6 migration guide - Application note
UBX-21010015 - R02 Migration between LARA modules Page 19 of 25
C1-Public
I2C devices as for example an audio codec: the module acts as an I2C host which can communicate
with I2C devices in accordance with the I2C bus specifications.
LARA-R2 modules do not integrate pull-up resistors on SDA and SCL lines: external pull-up resistors
have to be provided accordingly if the I2C interface is used in applications with LARA-R2 modules.
Instead, LARA-R6 series modules have internal pull-up resistors on SDA and SCL lines, so there is no
necessity of external pull-up resistors.
It is recommended to use the V_INT output to supply the module side of external voltage translators
connected to the I2C interface.
2.3.10 Digital audio interface
LARA-R2 and LARA-R6 series modules provide a compatible 1.8 V digital audio interface over the
I2S_TXD, I2S_RXD, I2S_CLK, I2S_WA pins, that can be configured by AT command to transfer digital
audio data to/from an external device as an audio codec.
The configurations available and supported by LARA-R2 and LARA-R6 series modules for the digital
audio interface may slightly differ: see the Audio sections in the u-blox AT commands manual
[6].
☞ LARA-R6001D / LARA-R6401D data-only product versions do not support voice / audio feature.
2.3.11 Clock output
LARA-R2 and LARA-R6 series modules provide a compatible 1.8 V digital clock output on the GPIO6
pin. This is mainly designed to feed the clock input of an external audio codec, as it can be configured
in “Audio dependent” mode (generated only when the audio is active), or in “Continuous” mode.
☞ LARA-R6001D / LARA-R6401D data-only product versions do not support GPIO6 clock output.
2.3.12 GPIOs
LARA series modules provide nine compatible 1.8 V GPIO pins (GPIO1-GPIO5, I2S_TXD, I2S_RXD,
I2S_CLK, I2S_WA) that can be configured as General Purpose Input/Output or to provide custom
functions (for further details, see the related data sheet of the modules
[1] [4], and the GPIO chapter
in the u-blox AT commands manual
[6]).
2.3.13 Antenna dynamic tuning
LARA-R6401 and LARA-R6401D series modules support a wide range of frequencies, from 600 MHz
to 2200 MHz. For such modules, to provide more efficient antenna designs over a wide bandwidth,
RFCTL1 and RFCTL2 pins can be configured to change their output value in real time according to the
operating LTE band in use by the module.
These pins, paired with an external antenna tuner IC or RF switch, can be used to:
• tune antenna impedance to reduce power losses due to mismatch
• tune antenna aperture to improve total antenna radiation efficiency
• select the optimal antenna for each operating band
2.3.14 Reserved pins
LARA series modules include pins reserved for future use, marked as RSVD, which can all be left
unconnected on the application board, except the RSVD #33 pin:
• It is recommended to connect to ground the RSVD #33 pin of LARA-R2 modules
• It is suggested to connect an accessible test point to the RSVD #33 pin of LARA-R6 modules