ebay 103c8t6 oled, nrf24, esp8266 + empty pads

for eeprom, spi flash, battery and tf sd socket @ £4.86
headers for oled, nrf24, esp8266 and bluetooth, uart and swd to 2×4 header

http://www.ebay.co.uk/itm/191974161480? … EBIDX%3AIT

a rather neat small board

stephen

I like this board.

Looking at BP board it seems there just be enough space for one WB SPI Flash chip on bottom side

Looks like it should work OK.

USB seems to be connected and there is a 1.5k USB pullup (which is correct)

i tried to post top and bottom pictures with my phone, wherever it saved them is up in the clouds

i also included an AAA battery for sizing, short side is 1 AAA in length, long side ~1.5??

sot pads for 24c02 and flash are marked as such, also more pads ( identified by D/R/C) for the support components, so i expect
some work in finding appropriate values, but straightforward work.

seems to have button on PA8, LED on PA1 ?? ??
headers,
2 off 2×20, [A0-A15, C14, C15, 3v3, GND] [ B0-B15, C13, 3v3, 5v, GND] 1 off 4×2 [GND, SWD, SWCK, 3V3] & [TXD, RXD, 5V, GND] 1 OFF 4X1 [3V3, GND, RX, TX]

pth for 5v & GND, regulator is an AMS117 type

if there are any conflicts is unknown, but someone put in time and effort. i wonder if i can find a schematic … … …
nrf24 and esp8266 at the same time ??

stephen

if you order 2, you save £1 on the price of 2 times 1 off. i did again

If you are planing on putting something on the 24c02 pads, consider using an AT24C256 or similar as it will fit on the same footprint and gives you 23k x 8bits (32kB) rather than the paltry 256 bytes of the 24c02. One off, the cost difference is not particularly significant.

Of course !
Even if 24C02 was already soldered, I would rather unsolder it and resolder a bigger one.

zmemw16: more pics requested ebay pic is a bit blurry

used phone, looked at dates 22-01-2005 bleep bleep
did it again & zoomed icon view

ok it saved them in 2005 – why oh why

dimensions – more like 1 x 1.25 AAA

took top and bottom, opened in gimp, did a really zealous crop, saved as xcf and exported as jpg (250k/500k)
redid as png – nope way too big
changed to greyscale
judges marks for readability please, n.b. tft-oled not labeled with pins

neat-tidy-top.jpg (87.26 KiB) Viewed 2649 times

– smt size look more 0806 (or even 0604), maybe both would fit, but forget 1208, they are much to big.
– soic8 and sop8 are synonym. Flash there soic8W (wide 208mil version)
– don’t use 24C02, place a 24C32 or higher such 24C512, they are pin compatible. (64KB vs 256 bytes)

Seems as if this thread is heading into the realms of vapourware as when I try to buy anything from the seller it’s “not accepting bids”

SMT size – my non-metric calibrated eye thinks 0805 or 1008 for D3 and D4 – just slightly less than the distance between the pins on the 0.1″ header.
However best to get out the calipers and check. => http://www.topline.tv/SizeChart.html

i must be a fan, just ordered 2 more.
i’m in the uk and shipping is list as from somewhere to the east.

STM32F103C8T6 ARM Minisystem Development Board STM32 Development Core Board CK…
STM32F103C8T6 ARM Minisystem Development Board STM32 Development Core Board CK
Estimated delivery: Thu. 15 Dec. – Wed. 18 Jan.

Item ID: 191974161480
Transaction Id 1333131683009
Quantity: 2

can anyone tell me a sensible price for a AT24C256 £1.81 for 10 off seems slightly suss
oh well they 35 orders and 10 for £1.87
https://www.aliexpress.com/snapshot/853 … 2632083200

stephen

just got a shipping notice for the boards.
srp

I ordered a couple of these boards from one of my regular suppliers and asked for schematics.

@ahull
and there was me thinking it’s just the 3 (1206 0805 0604) i need to worry about
link, bit overwhelming but useful.

@evildave_666
regular suppliers? price?

@roger
please snaffle those pics for the wiki if you want to. maybe slot it in above 103 with nrf24 and its variant 107 ?

stephen

the feline has found herself a cubby hole in one of my heaps, as she grooms, the whole of it rattles
she does a lot of grooming.

evidently she tidied house, disturbed a tin box full under there. almighty clang from it.
i don’t mind her stepping across me, but not in 2 bounds and all i get is a view of her tail. she could least say hello

zmemw16 wrote:i must be a fan, just ordered 2 more.
i’m in the uk and shipping is list as from somewhere to the east.

STM32F103C8T6 ARM Minisystem Development Board STM32 Development Core Board CK…
STM32F103C8T6 ARM Minisystem Development Board STM32 Development Core Board CK
Estimated delivery: Thu. 15 Dec. – Wed. 18 Jan.

Item ID: 191974161480
Transaction Id 1333131683009
Quantity: 2

can anyone tell me a sensible price for a AT24C256 £1.81 for 10 off seems slightly suss
oh well they 35 orders and 10 for £1.87
https://www.aliexpress.com/snapshot/853 … 2632083200

stephen

zmemw16 wrote:

@evildave_666
regular suppliers? price?

tx-hang strikes again. she does have some nice items.

£4.86 == $6.12 – close enough

isn’t that sch missing an oled connector ? saved anyway.

stephen

its in a smaller font and rotated, pin names are unreadable though
srp

I got my boards from TxHang today.

Generic 2.0 bootloader on pa1 binary from the github works fine. USB upload worked from the first go after getting the bootloader on.

Note that the swdio and swclk labels on the board’s silkscreen are swapped from what they should be. Also if it wasn’t clear, the TFT/OLED pins are just tied to the pins adjacent to them on the 20-pin header.

Post deleted (I read the Wicki! )

I have bought a few of those boards. One weird thing about them is that the SDA and SCL pins in the EEPROM pads are not connected to hardware I2C pins, but rather to PB4 and PB6. If you solder two 10k 0603 resistors to the R12 and R13 pads, you can use the PB4 and PB6 pins as software I2C pins without using external pullup resistors as you would by using the PB6 and PB7, which are the hardware I2C1 pins. You do need to modify the Wire.cpp in order to use the PB4 and PB6 pins. Now, here’s what is funny: PB4 and PB6 are used by both the SPI1 and Serial1 interfaces, which also have alternate pins. I wonder if someone could include an option in the Wire.h to let people choose which pins they use as I2C pins with a couple of defines, since what there is in place are two lines like:

// Declare the instance that the users of the library can use
//TwoWire Wire(SCL, SDA, SOFT_STANDARD);
//TwoWire Wire(PB6, PB7, SOFT_STANDARD); // this is how the wire.cpp file originally is
TwoWire Wire(PB4,PB6,SOFT_STANDARD); // EEPROM pins in the blackboard


please, please, it would be really nice if you put up a picture of whatever connections are hiding behind the board and display.

there is probably more documentation than anything else on this machine, from A Touch of Frost – lottery win – he lost it;
” paperwork Jack, i keep telling you, paperwork” !
or something close.

i’ve only just again found my SMT soldering station.
but my 24c256’s have arrived which is what prompted the search, solder is next … … … paper index after that !

stephen

zmemw16 wrote:please, please, it would be really nice if you put up a picture of whatever connections are hiding behind the board and display.

there is probably more documentation than anything else on this machine, from A Touch of Frost – lottery win – he lost it;
” paperwork Jack, i keep telling you, paperwork” !
or something close.

i’ve only just again found my SMT soldering station.
but my 24c256’s have arrived which is what prompted the search, solder is next … … … paper index after that !

stephen

@aroldorosenberg

i was after the circuit/sketch on the paper, there were some strange to me at least port numbers. i suspect that’s the esp socket?
for example my 103rc boards with just a nrf24 socket, it’s on spi 1 pins a4-a7 with cs & irq on port c4 & c5 istr

regarding alternate functions, 407xx pdf has 9 pages of it, i’m wondering if there’s the same or more for 103. what chance the same mapping ????

stephen

I was just trying to figure out which pins of the NRF24/ESP8266 connectors were connected to, it’s nothing other people haven’t found out already in this thread

regarding alternate functions, 407xx pdf has 9 pages of it, i’m wondering if there’s the same or more for 103. what chance the same mapping ????

well, found them and most definitely not the same format / mechanism
RM0008 Reference Manual STM32F101xx, STM32F102xx, STM32F103xx, STM32F105xx and STM32F107xx advanced ARM®-based 32-bit MCUs
November 2015 / DocID13902 Rev 16 / 1137 pages

and its 21 or so pages for the 103. start page may well be early at 174(182??) ends about 195.

stephen

I soldered in a micro-sd card slot and 3 10k resistors in the nearby pads, as per the schematic.

Guess what?

Works perfectly with the default SD library. Chipselect pin is PA4. It could use an activity led to indicate when the pin is pulled low, like on some micro-sd card readers.

i’ve just re-read this thread.
oh, so i didn’t actually need to solder those resistors in
srp

The cheap nrf24l01 modules most of us are familiar with work quite well on them, by the way. Both the small, with the PCB antenna, and the bigger one with a SMA one.

https://www.instagram.com/p/BPi56h-jUUe

Anyone a good schematic in pdf format for this board ?

https://s3-ap-southeast-1.amazonaws.com … 363817.jpg

that’s about as good as it gets, however most of it is boiler plate.
if you can find any one of PA4-PA7, that’s SPI1 etc.
same sort of thing for the I2C & UART’s etc
OLED might be a problem.

all a bit of match the blobs jigsaw

i just tried looking at it with GIMP, it is just about readable.

stephen

Thanks Stephen, but that’s exactly what i have found on the net. I would like to connect a NRF2401 and i can hardly read the pin#.

The NRF2401 Socket should be:

1 GND 2 VCC
3 PB0 CE 4 PB2 CSN
5 PA5 SCK 6 PA7 MOSI1
7 PA6 MISO1 8 PA15 IRQ

nrf24 8 pin signals
1 GND
2 VCC
3 PB0 CE
4 PB2 CSN
5 PA5 SCK
6 PA7 MOSI1
7 PA6 MISO1
8 PA15 IRQ


I have just noticed that the lowest ebay UK price for these boards has dropped by about 25% in the last few days:

http://www.ebay.co.uk/itm/272517368216? … EBIDX%3AIT

http://www.ebay.co.uk/itm/292046951651? … EBIDX%3AIT

With those radio pads, they look like they were designed with a specific purpose in mind, perhaps a Walkera DEVO 2.4GHZ remote clone, or some such device.. Interesting..

The Pins are certainly BP0 en BP2 as indicated on the diagram posted earlier. Those pins are respectively pin 18 and 20 on the STMChip – did the test with a multimeter. I can’t get the NRF module working using the (reworked) RF24 library. Did one of you got it working ? If so which library, any mods necessary ?
Thx

For NRF24 lib please have a look here: viewtopic.php?f=9&t=2028

Hi Stevestrong,
Sorry for late reply… got the NRF working on this board using the RF24-STM https://github.com/jaretburkett/RF24-STM. I Used the RF24(PB0,PB2) and used autoACK, dynamic Payload and enableackpayload features.
As already mentioned I use this for my DIY RC transmitter / drone. The ackPayload gives some info back from the drone ( Battery voltage, pressure, heading,…). Its already working on arduino, I’m trying to port the code to STM32 with the magnificent help of the video of Joop Brokking ( )

Happy 2018!

which video ?
srp

See on his website http://www.brokking.net or his YouTube channel. He did a series on a drone with an arduino, he is now preparing a series on a drone with STM32F103-board. Really instructive.

bad site, re-routes to www dot booking dot com

cheers ray.
there’s a space in the link – missed it completely.
srp

Sorry for th typo in the link, updated it.
https://www.youtube.com/playlist?list=P … LQVkDFHbxC For his videos on his STM32 drone project.
D

One possibly strange thing I noticed – the VBAT pin has diodes on it. One to the battery, one to VCC_3.3V. It looks like they want to relieve the battery when the power is on. But looking at the processor data sheet, it looks like it has provision for that internally. I haven’t seen other boards that have a provisioned battery backup, so I don’t know if it is really needed or if it is a standard practice. With simpler boards, I hope I can just connect the battery to VBAT and not worry about it.

[electrobling – Sun Jan 28, 2018 12:00 am] –
One possibly strange thing I noticed – the VBAT pin has diodes on it. One to the battery, one to VCC_3.3V. It looks like they want to relieve the battery when the power is on. But looking at the processor data sheet, it looks like it has provision for that internally. I haven’t seen other boards that have a provisioned battery backup, so I don’t know if it is really needed or if it is a standard practice. With simpler boards, I hope I can just connect the battery to VBAT and not worry about it.

I think the diode to VCC is to prevent the backup battery from powering the entire circuit when the main power source is removed. The internal diode was meant to protect against reverse voltage whilst the external added diode to VBAT may be a zener diode clamping the voltage to 3.3V.

It is hard to find boards that have an on board battery to seek guidance from. Most have VBAT as an external pin connection, or connected to VCC. But the Mini STM32 V3.0 and the LY-M3S STM32F103ZET6, which both have on board batteries, both have VBAT connected directly to the battery, with no additional circuits.

It will be a few weeks before my boards arrive, so I can’t try it, but it seems to me that the processor must adequately isolate the battery when power is off, and the designers of this board just got paranoid and threw the isolation diodes on without testing.

See 5.1.6 Power supply scheme on page 36/117 of the data sheet.

I’ll buy the explanation of battery reverse voltage, as it is possible to stupidly insert a coin battery backwards. However, I think the chances of a higher voltage than 3.3V appearing there are almost nil, so although it is a bit of mind reading without proof, I think the intention was to supply voltage from VCC in the absence of a battery. In other words, confusion. Or it was cloned from some other device.

Edit – this board does not have a removable battery, it’s soldered in. I think the ability to check polarity is assumed with the ability to solder.

Anyway, it is important to me because a working RTC is a big part of my plans.

istr @someone had blue smoke from a vbat pins shorted to usb vcc ?
srp

I read that one. I can’t find in now, but while looking for it, I noticed that the CZ mini STM32F103VET6 has the same diode circuit. Hmmm…. now I’m really wondering…

Edit – I should really download the other processor data sheets and compare. None of those are 103C version.

unfortunately i discovered with a cz_ministm32f103 that the 2.1mm external psu connection is a good fit to a 12v wall wart, missed the silk screen indicating it’s for a 5v one wry
not a good result

a very long time ago, i used a transformer 6v ac winding, full diode bridge and a 6v dc capacitor for smoothing.
i also discovered i could navigate 3 floors of stairs to the water tap with my eyes shut.
then again i’ve never repeated it either.

when looking at the schematics, we need to work out how the designer sees the peripheral devices.
it maybe that they don’t see them as straight out interfaces, but in order to get the required devices to meet their specifications they’ve used that ability to remap ( move ) them to different pins.
so we read the schematic and because of remapping means they’ve moved spi1 to the spi3 pins and i2c1, spi2, i2c2 … … etc as an example they might need both 3v3 & 5v tolerant spi interfaces, moving spi1 (portA 3.3v) to spi3 (portB 5v)
also they might as all the outside world (us) uses them rename(renumber) the interfaces spi1->sp3 spi2->spi1 etc
stephen

The USB on my board doesn’t seem to want to work. Checked the resistor values and they are correct, 20R to PA11 and PA12 and 1.5K pull-up to 3.3V. What could be wrong? I just received this board recently.

If you got blue pills, then do not wonder, 2 out of 10 cheap boards are statistically “bad”, showing not working USB, or not starting crystal.

[stevestrong – Fri Feb 02, 2018 5:13 pm] –
If you got blue pills, then do not wonder, 2 out of 10 cheap boards are statistically “bad”, showing not working USB, or not starting crystal.

After some inspection, it seems that pin 1 and pin 2 on the micro-usb connector seems to be shorted. Looks like I have to reflow that connector and see if it works properly after that.

First two pins are both tied to GND, that is normal.

Are you sure the bootloader is installed correctly?

I got 2 boards. I have to say, I’m impressed. Some things I like: UART1 comes out on a connector so you can install a bootloader without any soldering. There is an EEPROM chip factory installed (although I’m using the flash EEPROM emulation library at the moment). The compatible connections make it possible to add a cheap 64×128 OLED and ESP-01 and NRFL01 without any hardware mods or kludgy wiring. They provisioned the 32kHz oscillator and didn’t burden the crystal with external I/O connections. There are mounting holes, yay! Here is a shot of a clock project running:

CIN_1296.jpg (209.07 KiB) Viewed 606 times

Here are some board shots:

CIN_1279 (1) .jpg (230.94 KiB) Viewed 603 times

I have populated the microSD slot.

[zoomx – Sun Mar 25, 2018 6:28 pm] –
I have populated the microSD slot.

Great. I have 10 holders on order. I placed D3 so that VBAT is powered from VCC, even if there is no battery. That should improve LSE stability. If you use the LSE, and plan to never place a battery, the pads could be shorted to do that. I will pull a pin from the ESP socket and jumper CH_PD to PB14 so I can shut down the ESP-01 when it is not in use.

I could not source solder tab lithium batteries locally, so I found a way to install a battery holder:

CIN_1333.jpg (184.39 KiB) Viewed 364 times

I found the schematic for this board in a taobao listing.

It’s a PDF, and it seems like there’s also a pcb design file. What program uses .PCB?

There are also some larger files, but I can’t seem to download them without installing a chinese botnet app.

Check this out:

https://imgur.com/a/EguBdxq

[aroldorosenberg – Mon Feb 04, 2019 12:18 am] –
I found the schematic for this board in a taobao listing.

Great! Thanks for sharing your findings. The schematic posted earlier on the thread had some an annoying overlay. Unfortunately I don’t know the answer to your question.

I grabbed the images from the link aroldorosenberg posted in case the page disappears (and for easier viewing).

Board design:

Schematic: