Computer Systems (COS10004) - Raspberry Pi Labs

ARM assembly programming using RPi for Computer Systems (COS10004) at Swinburne University of Technology

Summary of RPi models

RPi Model	2B	2B v1.2	3B	3B+	4B
SoC	BCM2836	BCM2837	BCM2837	BCM2837B0	BCM2711
Memory	512MB	1GB	1GB	1GB	1/2/4/8GB
Peripheral Base address	0x20000000	0x3F000000	0x3F000000	0x3F000000	0xFE000000
GPIO Offset	0x200000	0x200000	0x200000	0x200000	0x200000

RPi 4B

RPi 4B Material

• USB Type-C (male) to USB Type-A (male) 5V/3.0A power supply. Important: not e-marked
• micro SD card (8GB or more)
• micro SD card adapter for computer
• breadboard
• a few LEDs
• a few resistors (between 47Ω and 330Ω approx.)
• a few cables to connect from GPIO pins (female) to the breadboard (male)
• electronic buttons (for the I/O labs)
• micro HDMI (male) adapter to computer lab screens (normally DVI)

RPi 4B micro SD card files

• start4.elf
• kernel.img - Writes 1 to GPIO18 pin (Will turn on an LED correctly connected to GPIO18)

Note that bootcode.bin is not required for RPi 4 because it is included in the EEPROM

RPi 3B+

RPi 3B+ Material

• micro USB Type-B (male) to USB Type-A (male) 2.5A power supply
• micro SD card (8GB or more)
• micro SD card adapter for computer
• breadboard
• a few LEDs
• a few resistors (between 47Ω and 330Ω approx.)
• a few cables to connect from GPIO pins (female) to the breadboard (male)
• electronic buttons (for the I/O labs)
• HDMI (male) adapter to computer lab screens (normally DVI)

RPi 3B+ micro SD card files

• start.elf
• bootcode.bin
• kernel.img - Writes 1 to GPIO18 pin (Will turn on an LED correctly connected to GPIO18)

RPi 3B

RPi 3B Material

• Same as RPi 3B+

RPi 3B micro SD card files

• start.elf
• bootcode.bin
• kernel.img - Writes 1 to GPIO18 pin (Will turn on an LED correctly connected to GPIO18)

RPi 2B v1.2

RPi 2B v1.2 Material

• micro USB Type-B (male) to USB Type-A (male) 1.8A power supply
• micro SD card (8GB or more)
• micro SD card adapter for computer
• breadboard
• a few LEDs
• a few resistors (between 47Ω and 330Ω approx.)
• a few cables to connect from GPIO pins (female) to the breadboard (male)
• electronic buttons (for the I/O labs)
• HDMI (male) adapter to computer lab screens (normally DVI)

RPi 2B v1.2 SD card files

• start.elf
• bootcode.bin
• kernel.img - Writes 1 to GPIO18 pin (Will turn on an LED correctly connected to GPIO18)

First steps

The first step is to check that you circuit works. Wire your circuit, put the provided files in the SD card, and power your RPi. If the LED connected to GPIO18 turns on, your can continue with the lab. If not, check if you are doing some of the typical errors:

• Wrong format of the SD card
• Wrong files in the SD card
• LED wrong connection (reversed polarity)
• Wrong wiring
• Wrong GPIO connected

SD card format

If the SD card doesn't have a FAT32 bootable partition, it won't work.

• 1 single partition
• FAT32
• Bootable partition

How to format the SD card

The following steps show how to format properly the SD card in GNU/Linux:

1. Plug the USB

2. Execute dmesg

   • This will tell you the name of your device. For example sdb:
   • [836119.568253] sd 4:0:0:0: [sdb] Attached SCSI removable disk
   • Some distros (such Arch Linux) might use mmcblkXpY notation

3. Umount all the partitions of the usb umount /dev/sdXY

   • X is the letter where your sd card is connected (probably not "a", be careful). In this example is "b"
   • Y is the number of the partition. You need to umount all the partitions from 1-N

4. Execute fdisk /dev/sdX

   • In fdisk you should delete all the partitions, command d
   • Create a single partition, command n
   • Make the partition bootable, command a
   • Change the partition type (command t) to "W95 FAT32" which is option b
   • Write the changes w
   • Exit fdisk q

5. Create an MS-DOS filesystem mkfs.vfat /dev/sdX1

6. Add the SD card files provided for your RPi to test it

Compiler

We will use the ARM assembly compiler FASMARM running under GNU/Linux, and windows.

GNU/Linux

You can use the binary from the full package download, or use the binary provided in this repo. To compile your code execute the following command:

./fasmarm test_RPI.asm

It will generate a binary file if it compiles without any errors. No compilation errors are indicated like this:

flat assembler for ARM  version 1.43 (built on fasm 1.73.02)  (16384 kilobytes memory)
1 passes, 36 bytes.

macOS

Wine is probably the best option.