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by raphaeldinge
Sat Jan 06, 2018 4:23 pm
Forum: Bare metal, Assembly language
Topic: Enabling MMU slows down VFP?
Replies: 5
Views: 674

Re: Enabling MMU slows down VFP?

@AlfredJingle Thanks for your reply In the meantime, I also made some code to enable the data cache, but I could see only an improvement when the MMU is setup as well, which makes sense anyway I guess. I've had a really hard time setting up the MMU, and I think I should really read more the datashee...
by raphaeldinge
Wed Dec 27, 2017 11:25 am
Forum: Bare metal, Assembly language
Topic: Enabling MMU slows down VFP?
Replies: 5
Views: 674

Re: Enabling MMU slows down VFP?

@dwelch67 Thanks for your reply. In my code I have different functions to enable or not the MMU (both do the instruction and branch cache though), and I could verify that multiple time. I will need to verify that the linker doesn't move addresses around but I'm pretty sure this is not the case (I ou...
by raphaeldinge
Tue Dec 26, 2017 2:45 pm
Forum: Bare metal, Assembly language
Topic: Enabling MMU slows down VFP?
Replies: 5
Views: 674

Enabling MMU slows down VFP?

I'm making the following performance test under different contexts : void measure_vmul_f32 (sys::Console & console) { asm volatile ("vmov.f32 s15, %0" :: "r" (0x3f800000) : "memory"); // 1.f asm volatile ("vmov.f32 s14, %0" :: "r" (0xbf800000) : "memory"); // -1.f auto start = sys::get_clock_us (); ...
by raphaeldinge
Sat Dec 23, 2017 7:18 pm
Forum: Bare metal, Assembly language
Topic: JustBoom DAC HAT (or any other I2S DAC HAT) on RPi 3?
Replies: 4
Views: 610

Re: JustBoom DAC HAT (or any other I2S DAC HAT) on RPi 3?

So thanks to @rst, I understand really more what is going on. As suggested, the PCM512x needs to be configured before it is used. Here are my notes so far : The configuration is done through I2C as visible here on Pin 3 & 5, which translates to GPIO 2 & 3, which in turns means that the I2C device nu...
by raphaeldinge
Sat Dec 23, 2017 2:20 pm
Forum: Bare metal, Assembly language
Topic: JustBoom DAC HAT (or any other I2S DAC HAT) on RPi 3?
Replies: 4
Views: 610

Re: JustBoom DAC HAT (or any other I2S DAC HAT) on RPi 3?

@rst Thanks so much for your quick reply! I think it contains exactly all the things I need to know to unblock me. Very appreciated.

I will report back progress when appropriate.

Thanks!
by raphaeldinge
Sat Dec 23, 2017 2:20 am
Forum: Bare metal, Assembly language
Topic: JustBoom DAC HAT (or any other I2S DAC HAT) on RPi 3?
Replies: 4
Views: 610

JustBoom DAC HAT (or any other I2S DAC HAT) on RPi 3?

Hi, I'm new to this forum and bare metal coding in general. Thanks already to all the information from the community that could get my project quickly started! :D I'm trying to make a JustBoom DAC HAT work, bare metal , on a RPi 3 Model B , for a personal project. I started to write a small C++ kern...

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