I got the 10 a few months ago, it was advertised as being able to use all (4) constellations simulatenously, but that was on an old ublox firmware, the current firmware has it limited to (3)
I’d be wary if that is a genuine U-block chip at that price. U-blox chips don’t use RS-232 serial, only TTL serial. I highly doubt at that price they would have added a TTL to RS-232 adapter, so if it is a genuine U-blox under the hood, test the serial out line first to see if it is TTL voltages (0-3V) or RS-232 (-50V to +50V) before you kill another U-blox chip. You never know with Aliexpress vendors as half the time the descriptions and specs of the item are wrong.
That being said, even if it is a fake they usually aren’t terrible compared to the real chips, though there are some duds out there. That all in one form factor is also a great one and done setup for the price they are charging.
I agree, but my bet is it’s RS-232 signaling with 0/3.3V rather than -12/+12V. I’ll bet your computer’s serial port will work just fine with the TTL levels without an extra converter. At least that is my experience with 0/5V TTL from the ancient Garmin puck.. -12/+12 is intended to handle long cables with substantial drop.
I’m sorry, but no. TTL serial is NOT RS232. And you CANT connect TTL serial to a RS232 pc port.
If I recall correctly then RS232 idles at -5V to -12V. A “0” bit is sent at +5V to +12V.
Where as TTL idles high(depending on io voltage this can be 1.2V to 5V and a “0” bit is sent at 0V.
You will notice that the polarity for a “0” bit is high for RS232 and 0V for TTL. The devices will NEVER be able to understand each other.
Also, pushing -5V to -12V into a TTL interface that is only designed for 0V to, say, 3.3V will destroy the TTL serial port.
The Garmin module might have output 0V at idle and 5V for "1”, but that might have been an out of spec RS232 design, designed to interface wiith RS232 voltages and with correct bit polarity. It was definitely not TTL if it worked directly with a pc serial port.
Sorry about the rant post, but I dont want others to connect TTL gps modules to pc serial ports and killing the gps modules…
I know this. And specificly stated it’s RS-232 and NOT TTL.
The RS-232 standard defines the voltage levels that correspond to logical one and logical zero levels for the data transmission and the control signal lines. Valid signals are either in the range of +3 to +15 volts or the range −3 to −15 volts with respect to the “Common Ground” (GND) pin; consequently, the range between −3 and +3 volts is not a valid RS-232 level. For data transmission lines (TxD, RxD, and their secondary channel equivalents), logic one is represented as a negative voltage and the signal condition is called “mark”. Logic zero is signaled with a positive voltage and the signal condition is termed “space”. Control signals have the opposite polarity: the asserted or active state is positive voltage and the de-asserted or inactive state is negative voltage. Examples of control lines include request to send (RTS), clear to send (CTS), data terminal ready (DTR), and data set ready (DSR).
This is RS-232 signaling. I know what it is. Yes a lot of them sold are TTL, I know that too. But this one isn’t and it more expensive (same manufacturer and shop) then the TTL versions they ALSO sell.
If they explicitly specify it’s RS-232 levels that it uses, I have to trust them on this.
As with all others they sell are stated it’s TTL and not RS-232.
1.5.3
GPS 18x LVC, GPS 18x LVC-5m, and GPS 18x-5Hz
These products interface to a serial port. The units accept TIA-232-F
(RS-232) level inputs and transmit voltage levels that swing from
ground to the positive supply voltage, TIA-232-F (RS-232) polarity.
They also have reverse polarity protection. The cable contains wires
for power, ground, receive, transmit, and measurement pulse output.
And yes, it works fine on a normal RS-232 port, I use them too
Just want to play with another device, as this Ali-receiver ticks all the boxes to connect directly to RS-232.
Bas - I’ve got both the Garmin 18x LVC and the Quescan QU10RP
One thing I noticed is the Garmin has a lot more ground wires (two thin and one thick) - whereas the Quescan only has one ground wire. At first I was a little leary, I didn’t want the power ground and signal grounds going back through the COM port. The little bit of runtime I do have on it, no issues so far - but I’ve only played around with it a little. I’m more happy with the LEA-M8T’s I’ve got, they allow survey-in, which is something not possible on the Quescan.
This is a straw man. I only noted that in my experience, computer serial ports in fact work with 5V TTL serial devices and relatively short cables, and that I suspect the same is true for 3.3V.
The title mentions DB-9 RS-232 but I wonder how much you can rely on that. While it’s entirely possible that U-Blox parts and/or boards incorporating them will fry in the presence of -12V/+12V, it’s also possible they are tolerant of those voltages despite being specified as 3.3V TTL. One cannot make assumptions across all TTL serial devices in the world. Certainly, if I were an EE at U-Blox, I would want to minimize customer returns and dissatisfaction by being liberal in what is accepted, as the Garmin 18x series is.
Unlike Garmin with the 18x series, u-blox does not provide products for consumers. They sell chips, or somewhat integrated modules around their chips, e.g., adding some of the external parts needed to make the chip work (e.g., EEPROM/flash, oscillators, LNA,…), and provide for a more accessible footprint (vs., e.g., QFN or even WL-CSP packaging). Turning those into a product suitable for consumers is the job of some integrator. E.g., when an integrator then advertises a product as “RS-232”, then it’s the integrator’s job to make the level-shifting happen, or provide for the tolerance for higher and/or negative voltages.
E.g., many of those cheap boards that are often considered “counterfeit” probably have a genuine chip in them, but everything else is provided by some integrator, even if the module on a board resembles one of those typical u-blox modules. E.g., those boards often provide for 5V power supply “tolerance” (common voltage regulator), but typically do not provide similar tolerance for the signal lines. Or they have an EEPROM holding some older firmware, which is too small to accept updates to more recent firmware versions.
Unfortunately, it is obviously bad for u-blox’s reputation when there’s issues with an assembled board. But not sure how to provide, e.g., for ±12 V tolerance on a bare chip to prevent that, or even one of their modules - especially when that is not relevant for their primary customer segments.
TTL uses positive voltages to represent a 1. RS-232 uses negative voltage to represent a 1. The two signals are incompatible, regardless of whether the devices are tolerant of the voltages, and as mentioned, would require a translator to flip the bits.
I was also wrong about the -50V to +50V. It’s a 50V range as the standard can have up to -25V to +25V. But there is also a -15V to +15V, and -5V to +5V RS–232 standards, so you are probably confusing a RS-232 device running at -5V to +5V in your mention.
Regardless, a TTL device such as a U–Blox chip would not be very tolerant of RS–232 voltages as Bas has shown in another thread when he fried a U-Blox GPS module hooking it up to a RS-232 serial port. Hence my warning to check the voltages output on the serial transmit line before hooking it up to the serial port.
