The Raspberry Pi Model B+ Q&A thread

[PeterO]

strange that you had a B with LED's in the Ethernet connector, normally they are simply absent.

Hence my embarrassment at thinking they has stopped working !
PeterO

[jojopi]

Model B Rev 2.1 actually does have the extra holes to accept a magjack with built-in LEDs. There are even pads R41/R42 to allow the signals to be routed to the magjack instead of to the separate LEDs. I do not know if any were ever made like that, though.

[notro]

OTOH the expanded GPIO header now means you have access to both the existing SPI0 (with 2 chip-selects) and SPI1 (with 3 chip-selects).

Is there a Linux driver for SPI1?

[AndrewS]

Is there a Linux driver for SPI1?

Dunno if anyone's written that yet. Even the current drivers for SPI0 (https://github.com/raspberrypi/linux/bl ... -bcm2708.c and https://github.com/raspberrypi/linux/bl ... -bcm2835.c) were written by members of the community Chris Boot and Stephen Warren...

[Gert van Loo]

Unfortunately the SPI1 and SPI2 modules are very different from the SPI0 so they have to re-write a lot of the SW.
The good news is that where the SPI0 is byte oriented, the SPI1 and 2 modules are more bit-oriented.
So you can interface with 12 bits SPI interfaces. e.g. a 12 bit ADC.

As I said elsewhere: the guy** who developed that module is a real genius.

**No guesses as to who that was

[jdb]

OTOH the expanded GPIO header now means you have access to both the existing SPI0 (with 2 chip-selects) and SPI1 (with 3 chip-selects).

Is there a Linux driver for SPI1?

You have the datasheet, don't you?

Get cracking!

Just send Gert a PM when you hit any apparent hardware bugs.

[jdb]

Model B Rev 2.1 actually does have the extra holes to accept a magjack with built-in LEDs. There are even pads R41/R42 to allow the signals to be routed to the magjack instead of to the separate LEDs. I do not know if any were ever made like that, though.

Rev 2.1 was brought in to partially bridge the BOM gap between Rev 2 and B+. In this design, certain high-value parts that would be differentiated between B and B+ were made interchangeable between the B rev 2.1 and the B+.

The ethernet jack is just such a part: the footprint on the rev 2.1 was modified such that it could accept a B+ ethernet jack with embedded LEDs.

[fruitoftheloom]

Just thought would post an update on my Raspian Wheezy install re power usage....................

USB Mouse, Keyboard, WiFi Adaptor and Bluetooth Dongle all plugged in to Pi

Has been working AOK with 5V2A PSU..

...but as I have a basic YouView TV (UK) Box with 2 USB ports which are enabled for power only, thought would see if it could do more than charge up my Phone. Purchased a thick USB Cable and the Pi is working AOK the Red LED staying solid, even whilst also charging phone, this was a surprise, but a pleasant one as one less power PSU.

[tlc]

Hi all.
I have a question about GPIO28 - GPIO31.
I have used them on B and A models for my RTC and SMT temperature modules and rpp PIC programmer.
When I migrated my SD to B+ uSD I forgot to disable RTC routine and get B+ USB ports OFF at the end of boot because of that.
After that I disabled it and it looks that no damage have been done to my B+ and uSD, (I have recreated uSD just to be sure that no damage is on filesystem) but I would like to know that for sure.
Does someone know to where are GPIO28-31 connected on B+ model, please? Or do I have to wait till the complete circuit diagram / schema will be released by the Foundation?
Thanks,
Tomas

[AndrewS]

Does someone know to where are GPIO28-31 connected on B+ model, please? Or do I have to wait till the complete circuit diagram / schema will be released by the Foundation?

According to https://github.com/raspberrypi/document ... /105/files

• GPIOs 28 and 29 are connected to I2C0 (possibly on the CSI and/or DSI interface?)
• GPIO31 is connected to "LAN NRESET" - driving this to the wrong value will have 'turned off' the LAN9514 chip, which is what will have stopped your USB ports (and Ethernet) from working

But yeah, waiting for the full schematics will be the only way to be 100% sure what the pins are connected to!

[plugwash]

That or a heat gun, a multimeter, fine pointed probes and a lot of patience.......

[mahjongg]

Does someone know to where are GPIO28-31 connected on B+ model, please? Or do I have to wait till the complete circuit diagram / schema will be released by the Foundation?

According to https://github.com/raspberrypi/document ... /105/files

• GPIOs 28 and 29 are connected to I2C0 (possibly on the CSI and/or DSI interface?)
• GPIO31 is connected to "LAN NRESET" - driving this to the wrong value will have 'turned off' the LAN9514 chip, which is what will have stopped your USB ports (and Ethernet) from working

But yeah, waiting for the full schematics will be the only way to be 100% sure what the pins are connected to!

According to a preliminary version 1.2 dated march 7 2014 of the B+ schematic in my possession, the above assesment is correct, and GPIO 30 is not used.
As its still a preliminary version its not 100% certain that it wasn't changed later though.

[tlc]

Thanks a lot for your answers.
I'm glad it looks that I have only temporarily shutdowned Eth+USB chip.
Camera module has not been connected at the first boot (neither was Eth).
Just keyboard and mouse.

Tomas

[wallarug]

Can someone please post a list of part IDs (J1, J2, J3, etc.) for the USB, Ethernet and ports on the B+. This is all I can find so far for the B+:
Model A Model B Model B+ Description
S1 S1 J1 Micro USB Power
S5 S5 J3 Camera
S2 S2 J4 Display
S3 S3 J6 HDMI
S6 S6 J7 Audio
P1 P1 J8 Main GPIO
IC2 IC2 U1E BCM2835

[AndrewS]

Can someone please post a list of part IDs (J1, J2, J3, etc.) for the USB, Ethernet and ports on the B+.

If you're compiling a list like that, you'll find http://www.raspberrypi.org/documentatio ... /README.md very useful Note that some of the part IDs are different between the Rev2.0 boards and Rev2.1 boards.

And maybe you'd find the CSV files from http://elinux.org/RPi_schematics_breakdown useful too? (haven't added Rev2.1, B+ or CM yet)

[rpdom]

From what I can see on the board:
USBs J11 (middle), J12 (edge)
Ethenet J10
GPIO (40-way) J8
RUN Not marked!
You've already got the others.

[wallarug]

From what I can see on the board:
USBs J11 (middle), J12 (edge)
Ethenet J10
GPIO (40-way) J8
RUN Not marked!
You've already got the others.

Thank you! I will see if I can find others from pictures.

This is the table so far: If anyone can fill in the B+ gaps, please let me know. (The ( - ) means not applicable.)

Current gaps: J2, J5, J9

Components: LAN9514, Reset Header

Model A Model B Model B+ Description
IC2 IC2 U1E BCM2835
IC3 IC3 LAN9512
P1 P1 J8 Main GPIO
P2 P2 - Video Core Debug
P3 P3 - LAN Debug
P4 P4 J10 Ethernet
P5 P5 - GPIO Header 8W
P6 P6 Reset Header
S1 S1 J1 Micro USB Power
S2 S2 J4 Display
S3 S3 J6 HDMI
S4 S4 - Composite Video Out
S5 S5 J3 Camera
S6 S6 J7 Audio
S7 S7 J11 USB mid
J12 USB edge

[rpdom]

J5 is the (unpopulated) JTAG connector on the other side of the board to the HDMI socket.

J9 is the micro SD card socket.

I can't see J2.

[wallarug]

J5 is the (unpopulated) JTAG connector on the other side of the board to the HDMI socket.

J9 is the micro SD card socket.

I can't see J2.

Which JTAG? ARM or VidCore?

[dom]

Which JTAG? ARM or VidCore?

J5 is VideoCore jtag.

[AndrewS]

J2 = the non-fitted RUN header (equivalent to P6 header on the ModelB)
J5 = the non-fitted VideoCore JTAG socket (equivalent to P2 header on the ModelB)
J9 = the microSD card slot ('equivalent' to S8 (regular SD card slot) on the ModelB)
U2 = LAN9514 ('equivalent' to IC3 (LAN9512) on the ModelB)

You may like http://elinux.org/RPi_Low-level_peripherals too (although it hasn't been updated for B+ yet).

[wallarug]

Which JTAG? ARM or VidCore?

J5 is VideoCore jtag.

Thanks Dom and Andrew for you help!

[mahjongg]

integrated circuits are not marked ICnn but Unn in the schematic, (from preliminary schematics) the list is:

• U1 BCM2835 SoC + PoP SDRAM (actually divided into several blocks, called U1a to U1q
• U2 LAN9514 USB Hub + Ethernet controller and PHY (U2a to U2c)
• U3 PAM2306AYPKE Dual switching power supply
• U4 APX803-46SAG Brownout detector (resetter)
• U5 AP7115-25SEG Low noise low drop 2.5V regulator (for Video DAC)
• U6 N.U.
• U7 N.U.
• U8 ESD5384 HDMI signal protection
• U9 AP2331W HDMI current limiter
• U10 AP7115-25SEG Low noise low drop 2.5V regulator (for PWM audio driver)
• U11 NC7WZ16 dual PWM driver
• U12 N.U.
• U13 AP2553W6 USB power manager
• U14 DMMT5401 Transistor array (ideal diode)

J2 is the RUN header.

[jojopi]

U6 N.U.
U7 N.U.

Interesting! These were originally going to be a pair of EMI4182 common mode filters for the four HDMI differential pairs. The same chips as on Model B Rev2.1, which was intended to reduce the number of BOM differences to the B+. Looking at B+ photos, they have been replaced by different filters, L4…L7.

U12 N.U.

With that gone, I do wonder whether Q6 is really still required?

[SomeGuy42]

Note that the PWR LED is now connected to an undervoltage supervision chip. The PWR LED will flash (or go out) if the PSU voltage drops below ~4.63V.

Is there a way to read input voltage with 'vcgencmd measure_volts' or something similar?