# Using the new CM4S module with eMMC on a CM3-panel-7-basic

<abstract>
This article explains how to use the new Raspberry CM4S module with eMMC memory
on-board on a CM3-Panel 7 basic terminal
</abstract>


## The new CM4S module

"<i>Based on the Raspberry Pi 4 Model B architecture, Compute Module 4S is intended for 
specific industrial customers migrating from Compute Module 3 or Compute Module 3+ and is 
not for general sale</i>". 

* <https://www.raspberrypi.com/products/compute-module-4s/>

<img src="./cm4s.jpg">

A [Raspberry Compute IO Board](https://www.raspberrypi.com/products/compute-module-4s/) 
is requested to transfer the OS on the eMMC memory of the CM4S module

## Step-by-step procedure description 

Download one of Raspberry Pi OS images available on this page:

* <https://www.raspberrypi.com/software/operating-systems/> 

This articles has been tested with Raspberry Pi OS Desktop and Lite version 64 bit May 3rd 2023  

Insert the [CM4S module](https://www.raspberrypi.com/products/compute-module-4s/) 
on the [Raspberry Pi compute module IO board v3](https://www.raspberrypi.com/products/compute-module-io-board-v3/) 

Place the J4 jumper on EN position the insert the USB SLAVE cable and then the POWER IN cable 

Instal the <code>usbboot</code> utility on your PC following this instruction:

* <https://github.com/raspberrypi/usbboot/blob/master/Readme.md#building>
 
The usb utility is used to boot the Raspberry Pi CM4S with a special firmware so that it emulates an USB Mass Storage.

<pre>
	$ sudo ./rpiboot
	
	RPIBOOT: build-date Sep 27 2023 version 20221215~105525 c4b12f85
	Waiting for BCM2835/6/7/2711...
	Loading embedded: bootcode.bin
	Sending bootcode.bin
	Successful read 4 bytes 
	Waiting for BCM2835/6/7/2711...
	Loading embedded: bootcode.bin
	Loading embedded: bootcode.bin
	Second stage boot server
	Cannot open file autoboot.txt
	Cannot open file config.txt
	Cannot open file recovery.elf
	Loading embedded: start.elf
	File read: start.elf
	Cannot open file fixup.dat
	Second stage boot server done
 </pre>

After that your eMMC will be visible as a normal microSD and you can save on it the Raspberry Pi OS image using 
the [Raspberry Pi Imager](https://www.raspberrypi.com/software/) software.

Inside the first partition called __bootfs__ edit the <code>cmdline.txt</code> file changing:

<code>console=serial0,115200</code>

in 

<code>console=serial1,115200</code>

Add these lines in <code>config.txt</code> file:

	#Ignore the HDMI cable hotplug (to avoid the delay at startup)
	hdmi_ignore_hotplug=1
	
	# Set the debug port on GPIO32, GPIO33 pins
	force_turbo=1
	dtoverlay=uart1,txd1_pin=32,rxd1_pin=33
	
	# Is not requested to insert this line
	#enable_uart=1
	
	# Activates the I2C 1 port on GPIO44 and 45 to talk with the
	# touch screen controller end camera crypto-chip
	
	# This line is deprecated
	# dtoverlay=i2c1-bcm2708,sda1_pin=44,scl1_pin=45,pin_func=6
	
	# Use this instead
	dtoverlay=i2c1,pins_44_45
	
	dtoverlay=goodix-7-acme
	
	## Enable the DPI port to talk with the TFT display
	dtoverlay=dpi18
	overscan_left=0
	overscan_right=0
	overscan_top=0
	overscan_bottom=0
	framebuffer_width=800
	framebuffer_height=480
	enable_dpi_lcd=1
	display_default_lcd=1
	dpi_group=2
	dpi_mode=87
	dpi_output_format=0x6f005
	hdmi_timings=800 0 40 48 88 480 0 13 3 32 0 0 0 60 0 32000000 6

and change 

* <code>dtparam=audio=on</code> in <code>#dtparam=audio=on</code>
* <code>dtoverlay=vc4-kms-v3d</code> in <code>dtoverlay=vc4-fkms-v3d</code>
* <code>max_framebuffers=2</code> in <code>#max_framebuffers=2</code>

Download this file:

* [dt-blob.bin](./dt-blob.bin)

and save it in on the bootfs partition

Download this file:

* [overlays/goodix-7-acme.dtbo](./goodix-7-acme.dtbo)
 
and save it in <code>overlays</code> directory.

### Enable the SSH server

By default the SSH server is disabled on the Rasperry pi OS standard microSD image. To enable it
create an empty file called __SSH__ with no extention on the first microSD partition. 
The ssh server will be enabled at first startup and you can reach the Linux command prompt
via lan.

	ssh pi@raspberrypi.local
	Password: raspberry

Turn-off the Compute Module IO Board and remove the CM4S

Mount the CM4S module on a CM3-Panel 7 basic and turn it on


## Differences between CM3+ and CM4S

|       | CM3+                  | CM4                   |
|-------|-----------------------|-----------------------|
| Chip  | Broadcom BCM2837B0    | Broadcom BCM2711      |
| CPU   | Cortex ARM 53 (ARMV8) | Cortex ARM 72 (ARMV8) |
| Clock | 1.2GHz                | 1.5GHz                |
| RAM   | 1GB LPDDR2            | 1GB LPDDR4-3200       |  
| Core  | 4                     | 4                     |
| Bit   | 64                    | 64                    |
| DIPS  | 3136                  | 7080                  |

## Links

* CM4S
	* [CM4S Product description](https://www.raspberrypi.com/products/compute-module-4s/) 
	* [CM4S Datasheet](https://datasheets.raspberrypi.com/cm4s/cm4s-datasheet.pdf)
* CM3+
	* [CM3+ Product description](https://www.raspberrypi.com/products/compute-module-3-plus/)
	* [CM3+ Datasheet](https://datasheets.raspberrypi.com/cm/cm3-plus-datasheet.pdf)
* [Compute module IO v3 schematic](https://datasheets.raspberrypi.com/cmio/cmio-schematics.pdf)
* [usbboot](https://github.com/raspberrypi/usbboot/blob/master/Readme.md#building)

## Device tree sources

### goodix-7-acme.dts
	
* [goodix-7-acme.dts](./goodix-7-acme.dts)

To compile it you need a Linux PC or a Raspberry Pi and a Device Tree Compiler:

	sudo dtc -@ -I dts -O dtb -o /boot/overlays/goodix-7-acme.dtbo /boot/overlays/goodix-7-acme.dts 

### dt-blob.dts

* [dt-blob.dts](./dt-blob.dts)

To compile it you need a Linux PC or a Raspberry Pi and a Device Tree Compiler:

	sudo dtc -I dts -O dtb -o /boot/dt-blob.bin /boot/dt-blob.dts

@include='bio_tanzilli'