What is purpose of I2C interface as well as GPIO, UART1, E_Clock and Sync_Pulse pins? Is it possible to power module directly from Li-Po battery charged up to 4,2V and what is power consumption depending on supply voltage?
Thanks!
Hi,
What is purpose of I2C interface as well as GPIO, UART1, E_Clock and Sync_Pulse pins? Is it possible to power module directly from Li-Po battery charged up to 4,2V and what is power consumption depending on supply voltage?
Thanks!
Hi,
The SE868-A GNSS module have a second communication port that supports I2C communication and Serial communication, pins 22 (I2C Data / TX1), 23 (I2C Clock / RX1).
SYNC_PULSE and E_CLOCK pins can be used to introduce an external clock signal and external timing to the GPS receiver, this advanced feature needs an external clock and external timing input with better accuracy than the GPS module itself and should not be used in general purpose applications.
It is not recommended to power the module directly with a battery, a good load regulation is recommended in order to prevent power supply glitches as the receiver transition between power states. We suggest putting an LDO between battery and module, in the official Reference design (that you can find in the Product User Guide) we use the PN: LP2985IM5-3.3/NOPB
I’m attaching the Family Product User Guide which reports the current consumption measurements in different working conditions that you can use as reference, to evaluate power consumption depending on supply voltage you have to take in account the efficiency of the DC-DC converter (i.e. the LDO) at different supply voltages.
Best Regards,
Simone Andrea Muscas Technical Support – EMEA Application Engineering Telit Communications S.p.A.
Thanks Simone!
Could you provide more info about I2C interface – speed,master or slave, enabled by default or not…
If this GPS module has SMPS with 2,8…4,3V range why to use additional linear regulator? Li-Po battery has low internal resistance and voltage range 3,3…4,2V and is charged by linear charger. I am expecting GPS to have less supply current at 3,8V.
Best regards
Thanks Simone!
Could you provide more info about I2C interface – speed,master or slave, enabled by default or not…
If this GPS module has SMPS with 2,8…4,3V range why to use additional linear regulator? Li-Po battery has low internal resistance and voltage range 3,3…4,2V and is charged by linear charger. I am expecting GPS to have less supply current at 3,8V.
Best regards
You’re welcome!
The SE868-A acts as a I2C slave device with:
I2C address 16 (0x10);
speed up to 400kbit/s;
internal buffer of 32 chars;
<LF> padding character (0x0A).
To achieve a good communication you simply have to read at good rate and discard padding characters, don’t forget to close PMTK commands directed to module with <CR> (0x0D).
The SE868-A hava an internal PMU that generates all voltages needed for module operation, having an external LDO helps providing a cleaner supply for the module. Your expectation is realistic but, the module support low power operation modes that can lead to significant power consumption reduction.
Best Regards,
Simone Andrea Muscas Technical Support – EMEA Application Engineering Telit Communications S.p.A.
Well, let me check if I am understanding i2c communication with module.
To send command:
i2c_start();
i2c_write(0x21);// 0x10 address shifted to MSB and added 0x01
i2c_write(…);//FIRST BYTE OF COMMAND
… // and remaining 31 bytes, includig command and’n’
i2c(stop();
To read NMEA:
i2c_start();
i2c_write(0x20);// 0x10 address shifted to MSB
i2c_read(1);
… // how many bytes to read here? Untill receiving all enabled nmea sentences?
i2c(stop();
About supply voltage – I will test it.
Now I am testing this module for a first time. It works perfect for it’s size! Well done Telit people!
The pseudoCode is ok but RnW bit is high for read and low for write, you should use address 0x20 to write PMTK commands and 0x21 for read NMEA sentences.
Since the internal buffer holds 32 chars you should read 32 bytes per time and wait 6ms between each read. If the last packet sent with I2C contains a valid PMTK command you should wait 36ms (30 for PMTK handling and 6 for buffer reload).
The latest firmware is the 3.8.4 and you can download it from T-Cloud at:
Simone Andrea Muscas Technical Support – EMEA Application Engineering Telit Communications S.p.A.
Thanks!
Hi Nikolay,
You’re welcome, to upgrade the firmware you must use T-Loaf (included in the firmware archive) opening a serial communication port (you can use a FTDI) to UART0.
Best Regards,
Simone Andrea Muscas Technical Support – EMEA Application Engineering Telit Communications S.p.A.
Hi Nikolay,
You’re welcome, to upgrade the firmware you must use T-Loaf (included in the firmware archive) opening a serial communication port (you can use a FTDI) to UART0.
Best Regards,
Simone Andrea Muscas Technical Support – EMEA Application Engineering Telit Communications S.p.A.
Hi,
What is purpose of I2C interface as well as GPIO, UART1, E_Clock and Sync_Pulse pins? Is it possible to power module directly from Li-Po battery charged up to 4,2V and what is power consumption depending on supply voltage?
Thanks!
Hi,
The SE868-A GNSS module have a second communication port that supports I2C communication and Serial communication, pins 22 (I2C Data / TX1), 23 (I2C Clock / RX1).
SYNC_PULSE and E_CLOCK pins can be used to introduce an external clock signal and external timing to the GPS receiver, this advanced feature needs an external clock and external timing input with better accuracy than the GPS module itself and should not be used in general purpose applications.
It is not recommended to power the module directly with a battery, a good load regulation is recommended in order to prevent power supply glitches as the receiver transition between power states. We suggest putting an LDO between battery and module, in the official Reference design (that you can find in the Product User Guide) we use the PN: LP2985IM5-3.3/NOPB
I’m attaching the Family Product User Guide which reports the current consumption measurements in different working conditions that you can use as reference, to evaluate power consumption depending on supply voltage you have to take in account the efficiency of the DC-DC converter (i.e. the LDO) at different supply voltages.
Best Regards,
Simone Andrea Muscas
Technical Support – EMEA Application Engineering
Telit Communications S.p.A.
Thanks Simone!
Could you provide more info about I2C interface – speed,master or slave, enabled by default or not…
If this GPS module has SMPS with 2,8…4,3V range why to use additional linear regulator? Li-Po battery has low internal resistance and voltage range 3,3…4,2V and is charged by linear charger. I am expecting GPS to have less supply current at 3,8V.
Best regards
You’re welcome!
The SE868-A acts as a I2C slave device with:
To achieve a good communication you simply have to read at good rate and discard padding characters, don’t forget to close PMTK commands directed to module with <CR> (0x0D).
The SE868-A hava an internal PMU that generates all voltages needed for module operation, having an external LDO helps providing a cleaner supply for the module. Your expectation is realistic but, the module support low power operation modes that can lead to significant power consumption reduction.
Best Regards,
Simone Andrea Muscas
Technical Support – EMEA Application Engineering
Telit Communications S.p.A.
Well, let me check if I am understanding i2c communication with module.
To send command:
i2c_start();
i2c_write(0x21);// 0x10 address shifted to MSB and added 0x01
i2c_write(…);//FIRST BYTE OF COMMAND
… // and remaining 31 bytes, includig command and’n’
i2c(stop();
To read NMEA:
i2c_start();
i2c_write(0x20);// 0x10 address shifted to MSB
i2c_read(1);
… // how many bytes to read here? Untill receiving all enabled nmea sentences?
i2c(stop();
About supply voltage – I will test it.
Now I am testing this module for a first time. It works perfect for it’s size! Well done Telit people!
FW is
$PMTK705,AXN_3.60_3333_14080800,C012,MT33-1.,1.106*55
Any advice about FW update (if new FW is available)?
BTW, the height of this module is 4 mm, not 6,1 mm, that is also great.
top
bottom
Hi
The pseudoCode is ok but RnW bit is high for read and low for write, you should use address 0x20 to write PMTK commands and 0x21 for read NMEA sentences.
Since the internal buffer holds 32 chars you should read 32 bytes per time and wait 6ms between each read. If the last packet sent with I2C contains a valid PMTK command you should wait 36ms (30 for PMTK handling and 6 for buffer reload).
The latest firmware is the 3.8.4 and you can download it from T-Cloud at:
https://tcloud.telit.com/public.php?service=files&t=acff14d2e4ab9715d3edbd70133bd935
Best Regards,
Simone Andrea Muscas
Technical Support – EMEA Application Engineering
Telit Communications S.p.A.
Thanks!
Hi Nikolay,
You’re welcome, to upgrade the firmware you must use T-Loaf (included in the firmware archive) opening a serial communication port (you can use a FTDI) to UART0.
Best Regards,
Simone Andrea Muscas
Technical Support – EMEA Application Engineering
Telit Communications S.p.A.
Yes, it is very easy to do that.