R404 issues


In R404 Not working (enumeration and power brown out) @ryanHologram mentions “Our conversations with u-blox and further testing continue to show that the R404 is not ready for prime time production scenarios”. Are there issues other than the re-enumeration stuff?

Also, I’m puzzled by the continuous mentions of power consumption. The R404 and R410 are LTE-only and they power consumption is actually pretty darn low! Is this just because you guys can’t keep 3G and LTE Cat-1M apart?

Specifically, the R404 and R410 accept Vcc in a wide range (3.2V-4.2V) and the peak current during TX is 490mA, avg max being 190mA. A 400mV voltage drop is allowed during TX. This should not be that much of a burden on an rPi unless you’re running the rPi itself very hot at the same time (unlikely when people are testing as in the mentioned thread). Note that when using 2G (not avail on the R404/R410) the peak TX current is 1.9A, yowza!


In my testing, the R404 was incredibly unreliable to get to start. I have a Pi Zero without wireless, and a Zero4U USB expansion board that draws power straight from the 5V rail to get around the current limit on the Pi Zero’s OTG port. Using a generic charger I could never get the board to start. Once I had an official Pi charger, I could sometimes get it to start, and if it actually started I could sometimes get it to enumerate. What made this incredibly frustrating is that, as other users here have mentioned, for some strange reason the R404 will be wholly incapable of booting up after being powered down until several minutes have passed. So if it fails to boot, it means you have to wait 5 minutes or so before trying again. And even if it does boot up successfully and enumerate, you only have until you shut everything off before that ceases to be the case.

So, from my independent testing, I would agree with the assertion that it does not appear ready for prime time. I would love to trade up to the R410 (which wasn’t available when I joined Hologram) to see if it has solved these problems. I’ve sent a support e-mail saying as much, but haven’t heard a response yet. Here’s hoping!


My question was actually more about issues other than the re-enumeration and initialization problems. I’m using the UART interface so I’m not plagued by those it appears so far.


Has anyone heard back about this issue? The first boot works for me on every pi at the shop, but lights fail after rebooting the pi.


n7, the ‘official’ word appears to be that the R410-based design does not have these issues, though I have heard nothing back from Hologram about being able to exchange my R404 for one as of this moment. I may just have to bite the bullet and buy one outright, or find another solution altogether.

tve, I looked into the UART interface but it appears that I would have to physically modify the unit in order to access such a mode. It is promising to hear that the UART does not appear to be affected by the same problems the USB interface is, though considering the USB interface is the only ‘officially’ supported way to interact with the modem, it does make sense that Hologram’s solution would be to abandon the R404 design in favor of the R410.


Thanks for the reply. Hopefully they will let us swap up. We are working on an unattended solution so reboot is pretty important. Keep me posted if you hear anything back from them. I’ll do the same.