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by baantonia
Mon Jun 25, 2018 1:44 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Trouble Connecting an RF Module over SPI
Replies: 9
Views: 716

Re: Trouble Connecting an RF Module over SPI

I might be completely wrong but looking at the documentation on page 11, the column "Type" appears incorrect for the use for pins 2 and 3, are they round the wrong way?
by baantonia
Wed Aug 23, 2017 7:03 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: DMA and SPI documentation
Replies: 5
Views: 1378

Re: DMA and SPI documentation

Thank you, your notes provide answers to a number of my questions.
by baantonia
Wed Aug 23, 2017 6:05 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: DMA and SPI documentation
Replies: 5
Views: 1378

Re: DMA and SPI documentation

Anything more useful than the Broadcom pdf would be great, thank you. The pdf provides vague instructions and very limited information on how each part interacts.
by baantonia
Wed Aug 23, 2017 5:34 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: DMA and SPI documentation
Replies: 5
Views: 1378

Re: DMA and SPI documentation

One of my issues is in understanding how individual bytes can be sent and received, as in polled mode, when writing to the FIFO 32bits are written, are the top 24 ignored? I'm trying to recreate the polled mode which sends and receives bytes for communicating with a mcp3002. Interesting you say you'...
by baantonia
Wed Aug 23, 2017 4:39 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: DMA and SPI documentation
Replies: 5
Views: 1378

DMA and SPI documentation

Apart from the Broadcom Peripheral documentation, is there anywhere, documented use of DMA, especially with SPI? I'm trying to understand how I can communicate with a SPI device via DMA, initially using a mcp3002 which is on the Gertboard. I have been able to copy memory contents from one place to a...
by baantonia
Sat Aug 05, 2017 8:39 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Number of SPI CS lines
Replies: 5
Views: 997

Re: Number of SPI CS lines

Or as an alternative, just use SPI0 with its two CS lines and a single MAX11040K and use extra GPIO pins to multiplex the analogue inputs.

Does this sound sensible?
by baantonia
Sat Aug 05, 2017 7:59 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Number of SPI CS lines
Replies: 5
Views: 997

Re: Number of SPI CS lines

Hmmm....... Maybe mix and match. Use SPI0 for the USB interface and SPI1 to read from the ADC chips but still using extra GPIO pins for their selection. Makes sense as it would simplify the configuration and round robin tasks. Plan to use CS through 4 OR gates along with the GPIO lines for chip sele...
by baantonia
Sat Aug 05, 2017 7:04 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Number of SPI CS lines
Replies: 5
Views: 997

Number of SPI CS lines

I need to control 3 or more SPI slaves and am just confirming that I'm not going up a dead end before I proceed programming a solution. My question is: Is there any reason why other GPIO pins cannot be used as CS lines as long as at least one of the actual SPI CS are asserted low? I plan to use a MA...
by baantonia
Mon Apr 24, 2017 11:04 pm
Forum: Bare metal, Assembly language
Topic: Printing characters on monitor connected to raspberry pi 3?
Replies: 10
Views: 1594

Re: Printing characters on monitor connected to raspberry pi

I'm gradually building up a library of routines, not great but works. Haven't looked at this for a few months, was in the process of checking out pwm. The codes target is for a pi zero but can be changed in the settings. However it does use the mailboxes and creates a framebuffer to output to the sc...
by baantonia
Mon Apr 24, 2017 2:07 pm
Forum: HATs and other add-ons
Topic: Rpi3 Bv1.2 & Gertboard 21-Oct-2012
Replies: 7
Views: 4746

Re: Rpi3 Bv1.2 & Gertboard 21-Oct-2012

I've used ribbon cable with dupont female to male jumper connectors to get access to the other GPIO pins otherwise hidden by the Gertboard. It's not pretty and doesn't allow the Gertboard to sit flat but it works. I agree, the Gertboard is an excellent tool!
by baantonia
Mon Apr 24, 2017 8:22 am
Forum: HATs and other add-ons
Topic: Rpi3 Bv1.2 & Gertboard 21-Oct-2012
Replies: 7
Views: 4746

Re: Rpi3 Bv1.2 & Gertboard 21-Oct-2012

Never used an Arduino so I cannot comment regarding interfacing directly or indirectly. Note: GPIO 0 and 1 on the Gertboard becomes GPIO 2 and 3 when connected to anything other than an original Pi B. However, the Gertboard does offer some level of protection for the RPi as the IO connections neares...
by baantonia
Sun Apr 23, 2017 11:16 pm
Forum: HATs and other add-ons
Topic: Rpi3 Bv1.2 & Gertboard 21-Oct-2012
Replies: 7
Views: 4746

Re: Rpi3 Bv1.2 & Gertboard 21-Oct-2012

Connect the Gertboard to the 26 pins furthest away from the USB and RJ45 connectors. Also, if not using the ribbon, place the Gertboard so it does not stack over the RPi, they appear as to be side by side. If using the ribbon cable, make sure the same arrangement applies. Using a ribbon cable does g...
by baantonia
Thu Apr 20, 2017 9:54 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: SPI Interfacing
Replies: 2
Views: 414

Re: SPI Interfacing

I've tried it and have also failed! There is nowhere on the forums or the web I have found to provide a clue. The BCM2835 document says it is available but provides no instructions of its use. This is something I too would like to investigate. https://www.raspberrypi.org/forums/viewtopic.php?p=10256...
by baantonia
Wed Apr 19, 2017 9:35 am
Forum: Advanced users
Topic: WiFi client as bridge.
Replies: 2
Views: 754

Re: WiFi client as bridge.

Have a look at viewtopic.php?p=733647#p733647 and the ongoing thread.
I use Pis to bridge Trend boiler monitors to our WiFi.
by baantonia
Sat Apr 08, 2017 6:47 am
Forum: Advanced users
Topic: How to have pi respond to calls over ethernet
Replies: 2
Views: 597

Re: How to have pi respond to calls over ethernet

I have actually done this to remotely "Press the on button" on another computer to turn it on by wiring up a relay to be controlled by a Pi via a GPIO pin. However you probably don't use RISCOS so the code is not very useful but the concept might be. I wrote, some time ago (1997 approx), a inetd equ...
by baantonia
Thu Apr 06, 2017 4:58 pm
Forum: HATs and other add-ons
Topic: Gertboard
Replies: 1
Views: 2477

Re: Gertboard

The Gertboard doesn't notify itself to the OS, you have to write software to control the devices on the board through the GPIO pins or run someone else's software.
by baantonia
Mon Mar 13, 2017 10:33 pm
Forum: HATs and other add-ons
Topic: PaPirus functions
Replies: 3
Views: 802

Re: PaPirus functions

Just discovered it’s an optional connection to a GPIO breakout board.
by baantonia
Mon Mar 13, 2017 10:17 pm
Forum: HATs and other add-ons
Topic: PaPirus functions
Replies: 3
Views: 802

PaPirus functions

I've recently purchased a PaPirus Hat with a 2,7 inch SPI ePaper display which is connected via a FFC and has 4 buttons connected to GPIOs 16, 26, 20, 21. So far I haven't looked into using the display and buttons but have discovered the hat also comprises an I2C RTC, with which I have been experime...
by baantonia
Wed Feb 15, 2017 9:52 am
Forum: Compute Module
Topic: CM3 as SPI Master ?
Replies: 4
Views: 1190

Re: CM3 as SPI Master ?

I've attempted on other Pis but failed SPI slave mode. I have a CM1 but don't have a CM3 yet, one on order. Seems an issue across all versions? If it can be done I'm not sure what I'm doing wrong. So far have found no code to compare against. As far as I can see data gets placed into the FIFO but do...
by baantonia
Tue Jan 31, 2017 12:50 pm
Forum: Bare metal, Assembly language
Topic: SPI wrong data out
Replies: 6
Views: 1663

Re: SPI wrong data out

ALT0, value 4, appears correct for the GPIO pins as you set this then later change them to input, value 0, but I do find that the read enable bit, bit 12 in the CS needs to be set. I too was scratching my head for some time why my bare metal SPI code wasn't working, but was working with a module wro...
by baantonia
Fri Dec 23, 2016 7:47 am
Forum: Bare metal, Assembly language
Topic: Pi zero gpio
Replies: 3
Views: 1509

Re: Pi zero gpio

Thank you, I have not investigated LED settings for the zero, that is useful information which I have not come across in my searches.
by baantonia
Wed Dec 21, 2016 12:16 pm
Forum: Bare metal, Assembly language
Topic: Pi zero gpio
Replies: 3
Views: 1509

Re: Pi zero gpio

I've found the PiZero to have the same GPIO memory mapping as the B+ starting at 0x20200000. Setting GPIO 47 to output also sets all the other GPIO registers in that bank to input as a by product, but that's not important in the scheme of things. Yes GPIO 47 should be set at the end of your code, wh...
by baantonia
Fri Oct 14, 2016 11:57 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: SPI/BSC SLAVE peripheral problems
Replies: 8
Views: 4641

Re: SPI/BSC SLAVE peripheral problems

I've been trying on and off for a few months now without any luck using some bare metal code to transfer data to another Pi via SPI as a slave. The FIFO appears to fill but nothing gets written onto the wire, very frustrating! Had an oscilloscope on the MISO wire, nothing. I think I did test a count...
by baantonia
Thu Oct 13, 2016 11:30 pm
Forum: Compute Module
Topic: Compute module 3 datasheet
Replies: 6
Views: 3345

Re: Compute module 3 datasheet

I've been trying and failing to get GPIO18-GPIO21 mode 3 functions (SPI slave) working for some time now using the original documentation with a range of Raspberry Pi, including the CM1. I see in this datasheet there are empty spaces. Was this function ever really available?
by baantonia
Wed Aug 31, 2016 6:39 am
Forum: Bare metal, Assembly language
Topic: Suspicious atags address
Replies: 10
Views: 2143

Re: Suspicious atags address

Does anyone have any clues why the SPI slave FIFO doesn't release data, I've been stuck on this for a few weeks and am now seriously considering the slower I2C master/slave route instead.

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