houkime | there are two variations in this family of sensors. TMD26721 like TMD26711 has i2c voltage = vdd. TMD26723 has i2c at fixed 1.8v | 00:31 |
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houkime | the part used in neo900 schematics is TMD26713 and it is powered from 2.7v | 00:31 |
houkime | (ie a part with fixed 1.8v i2c from a previous family) | 00:33 |
houkime | so the logical move is to employ TMD26723 | 00:33 |
DocScrutinizer05 | :nod: | 00:34 |
houkime | however availability of TMD26723 seems to be quite low. For example, on Digikey while the part is "active" there are 0 available immediately. | 00:35 |
DocScrutinizer05 | our daily business for almost a year, just we rarely did discuss it publicly | 00:37 |
DocScrutinizer05 | there's a lot more work in design than an occasional visitor would expect | 00:38 |
houkime | most of neo900 parts are ok in this regard except for oldies that are needed for compat and that are sourced from original n900. | 00:40 |
houkime | I am rechecking them as i go through courtyards and layout. | 00:41 |
Joerg-Neo900 | lis302 is EOL afaik | 00:41 |
Joerg-Neo900 | a few more as well | 00:41 |
Joerg-Neo900 | bq27200 | 00:42 |
Joerg-Neo900 | wpwrak had a script to check *all* components | 00:42 |
houkime | bq27200 will need to be sourced because it is a compatibility part(( | 00:43 |
houkime | we have already discussed this one earlier | 00:44 |
Joerg-Neo900 | well, leste isn't the 100% compatibility approach Neo900 was designed for. So it's questionable if this reqzurement is worth anything at all, adter all | 00:50 |
Joerg-Neo900 | unless you use genuine maemo dremantle, it won't matter | 00:51 |
Joerg-Neo900 | fremantle even | 00:51 |
houkime | I checked ams website. Pretty much everything optical measuring which uses 1.8 i2c is out of stock. | 00:51 |
houkime | however there was one more manufacturer that sdoes similar parts, called TAOS | 00:52 |
Joerg-Neo900 | We git some 3V3 I2C chips | 00:56 |
Joerg-Neo900 | thus a 3V3 bus, behind level shifter | 00:56 |
houkime | ah, taos is just one of the ams's properties it seems. | 00:57 |
Joerg-Neo900 | those some other chips also were not available 1V8 | 00:57 |
Joerg-Neo900 | sucks since it's just a logic level issue | 00:59 |
Joerg-Neo900 | I2C is OC | 00:59 |
Joerg-Neo900 | worts case use two FETs to levelshift I2C just for this chip | 01:00 |
Joerg-Neo900 | BOM +2 :-/ | 01:00 |
Joerg-Neo900 | avctually +4, you need 2 pullup R too | 01:01 |
Joerg-Neo900 | see hackerbus whitepaper for discussion of FET levelshifters | 01:01 |
houkime | 3.3v should be ok | 01:05 |
Joerg-Neo900 | houkime: if you vould finf a simplr singlewire 1/0 sensor without any programming, this would be great. But seems they are not fasgionabke anymore | 01:07 |
Joerg-Neo900 | fashiomable* | 01:07 |
Joerg-Neo900 | whatever, afk cu | 01:07 |
houkime | Joerg-Neo900, see ya. | 01:08 |
houkime | Joerg-Neo900, I couldn't find any details on proximity sensor for stylus detection in whitepapers. | 13:30 |
houkime | Joerg-Neo900, and in stuff also for that matter | 13:30 |
houkime | Joerg-Neo900, what i want to know is allowed wavelength range, power consumption and calculations for aperture diameter in LOWER. | 13:31 |
houkime | the position of the stylus bay i can calculate from the wpwrak's scans myself. | 13:32 |
houkime | Joerg-Neo900, i have little idea now about bay wall reflection spectrum. | 13:34 |
DocScrutinizer51 | houkime: I'm sorry for missing details in whitepaper. Wavelength is irrelevant, Appertures (plural) size depends on sensor design, the idea I tried to | 13:34 |
houkime | can't one have only one aperture (via hanging sensor from the lower side of the UPPER?) | 13:35 |
DocScrutinizer51 | sketch yesterday is: sensor sends throuch one apperture and receives through a second. Both appertures get "shu" by stylus | 13:35 |
DocScrutinizer51 | shut | 13:36 |
houkime | ok, so two apertures are for led and detector itself. got it | 13:36 |
DocScrutinizer51 | purpose of proto_v2 is (among other) to verify functionality of this design | 13:38 |
houkime | so what we are looking for here is very narrow angle for emitting LED, almost a laser-like thing, Otherwise it will illuminate LOWER and the integrated reflection power from LOWER will be much greater than from a tiny aperture. | 13:42 |
houkime | or rather, one should look at detection and LED emission cones, make sure that they intersect well at the depth of the bay | 13:55 |
houkime | and then make an artistic orifice based on these cones in LOWER | 13:55 |
houkime | which might turn out to be either 2 separate orifices or one merged. | 13:56 |
houkime | TMD49033 looks nice. It is multi-wavelength and can detect color. Same footprint as other TMDs which we already have. 1.8v all across. | 15:02 |
houkime | but it doesn't have a datasheet. though knowing ams it is probably included in TMD49031 datasheet or sth | 15:03 |
houkime | checking | 15:03 |
Joerg-Neo900 | houkime: the sensor was planned to get mounted onto S2 looking *down*ward through apperture un PCB S1-S2 | 15:03 |
Joerg-Neo900 | the idea is to have receiver optically separated from LED when some object sits on surface S1 | 15:04 |
houkime | Joerg-Neo900, separation is not necessary since this kind of sensors can measure yield and compare it with reference | 15:04 |
houkime | basically it measures distance by comparing integrated reflection | 15:05 |
Joerg-Neo900 | go ahead as you think works best | 15:05 |
Joerg-Neo900 | just keep in mind this sensor is always-on and thus will have massive impact on battery standby time | 15:06 |
Joerg-Neo900 | it should have active supply current <1mA | 15:06 |
Joerg-Neo900 | ideally <<1mA | 15:06 |
Joerg-Neo900 | average | 15:07 |
Joerg-Neo900 | if it doesn't "out of the box", you might need to define a sort of "polling" scheme driven by CPU that enables sensor every 5s for 0.01s or whatever | 15:08 |
houkime | Joerg-Neo900, the number of pulses per measuring act is programmable and less pulses are needed for smaller distances | 15:08 |
houkime | Joerg-Neo900, they don't need polling because they have a configurable interrupt pin | 15:08 |
houkime | Joerg-Neo900, though to configure it one probably needs to calibrate it and then write needed values into i2c registers | 15:09 |
Joerg-Neo900 | as I said: >>if it doesn't "out of the box", you might need ...< | 15:09 |
houkime | Joerg-Neo900, well, it technically doesn't work out of the box)) it needs calibration ad experiments. | 15:10 |
Joerg-Neo900 | initializing is "OOTB" | 15:10 |
houkime | ok | 15:10 |
Joerg-Neo900 | just needs to run autonomously after that, with a supply current average <<1mA | 15:10 |
Joerg-Neo900 | funny little detail that even works for N900: insering a lamba/4 antenna into stylus bay will massively improve FM TX ;-) the antenna is parallel to stylus and would get coupled to such l/4 | 15:14 |
Joerg-Neo900 | re stylus sensor, I also pondered mechanical switch (EEEWW!) and even capacitive "touch" sensor directly to a GPIO pin that senses statical charge movement in stylus plastic and change in capacitor value of the sensor pad to verify status inserted/removed | 15:16 |
houkime | alas. In stock on Digikey but no datasheet on the ams website after all. Such a mess. | 15:25 |
houkime | going to next candidate. | 15:26 |
DocScrutinizer51 | bydy, its a PITA | 15:28 |
DocScrutinizer51 | btdt even | 15:28 |
houkime | datasheet is present though on alldatasheet.com | 15:37 |
houkime | need to check remaining other candidates regardless | 15:38 |
houkime | though all these sensors are so expensive... 5-6 dollars for a proximity thing. oh man... | 15:40 |
Joerg-Neo900 | prohibitive pricing | 15:45 |
houkime | it might be even better idea to have led and sensor separate at this point and sensor just have a programmable interrupt on too much/too little light. | 15:45 |
Joerg-Neo900 | rule of thumb: sourcing * 3, so almost 20$ for stylus sensor isn't a selling point | 15:46 |
Joerg-Neo900 | those reflexive lightbar sensors were always a PITA | 15:47 |
Joerg-Neo900 | prolly there are more sensor concepts where LED is separate component | 15:48 |
Joerg-Neo900 | I see soap dispensers with lightbar, sold for like 8 bucks | 15:49 |
houkime | due to small distance needed in neo900 led could be so weak that it can be just always on wherever phone is on. | 15:51 |
houkime | so no flashing circuitry or whatever. | 15:51 |
DocScrutinizer51 | duh, that would cause at least 0.5 to 1mA | 15:51 |
DocScrutinizer51 | and sensing unmodulated light level is a nogo regarding noise rejection and reliability | 15:52 |
Joerg-Neo900 | if you really wanna go that route, you need a LED controlled by a CPU GPIO to pulse it with a duty cycle of <0.001% and detect the pulses on a A/D converted photodiode. Nasty but feasible | 16:04 |
Joerg-Neo900 | even I would opt against that stylus detection feature based on this concept. But in the end it's your design now | 16:05 |
Joerg-Neo900 | "even I" since I'm notorious for my featuritis | 16:08 |
clapont | hi everyone | 16:12 |
Joerg-Neo900 | hi | 16:14 |
houkime | SI1151-AB00-GM looks kinda nice compared to ams stuff. | 17:28 |
houkime | 1.8 bucks | 17:28 |
houkime | no integrated LED but LED driver instead | 17:29 |
houkime | interrupt pin, all things programmable | 17:29 |
houkime | 1.8v all across (excluding LED which has separate power) possible | 17:29 |
houkime | and the LED can be basically just any LED under 5.5v | 17:30 |
houkime | both visible and IR | 17:30 |
houkime | maximum sensitivity in blue area | 17:31 |
houkime | so it is bring_your_own_LED proximity sensor thing | 17:31 |
houkime | https://www.silabs.com/documents/public/data-sheets/si115x-datasheet.pdf | 17:33 |
houkime | it also configurably limits LED current | 17:34 |
houkime | though maybe 1.8 bucks + LED is still a bit much. | 17:35 |
houkime | Joerg-Neo900, what do you think? | 17:35 |
houkime | should look cool though if optical - you can probably look in the hole and see it blinking. | 17:36 |
houkime | if duty cycle and measurement pulses count permit that is) | 17:37 |
houkime | it has autonomous mode, so you just set up a timer via i2c and it measures every now and then. | 17:45 |
Joerg-Neo900 | sounds excellent, price is bearable. I suggest blue LED then, best efficiency, power LED from VBATT_SWITCHED | 18:32 |
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