Difference between revisions of "Embedded Open Modular Architecture/EOMA68/Tablet"
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Popular by decree, but only successfully-sold when the price is stunningly low yet the feature-set rich, tablets are the "must-have" for all ODMs and OEMs who aspire to a chunk of the large apple pie. Key goals for this motherboard are therefore to be small, slim, low BOM and low-risk development. Thanks also to the modular design, the board is sufficiently simple that it may even be possible to do as a 2-layer PCB, thus reducing costs even further. | Popular by decree, but only successfully-sold when the price is stunningly low yet the feature-set rich, tablets are the "must-have" for all ODMs and OEMs who aspire to a chunk of the large apple pie. Key goals for this motherboard are therefore to be small, slim, low BOM and low-risk development. Thanks also to the modular design, the board is sufficiently simple that it may even be possible to do as a 2-layer PCB, thus reducing costs even further. | ||
+ | |||
+ | = Connectors and Components = | ||
+ | |||
+ | The connectors required are: | ||
+ | * 1x USB2 | ||
+ | * PCMCIA Connector "inline" (signals conforming to [[Embedded_Open_Modular_Architecture/PCMCIA|EOMA/PCMCIA Standard]]) | ||
+ | * 5V Power | ||
+ | * 1x PCI Express "inline" (supporting USB Wifi, not PCI-e Wifi, such as RT2070 and RT3090) | ||
+ | * 1x Stereo Speakers and Microphone | ||
+ | * 1x RGB/TTL LCD Output (with LED Backlight) | ||
+ | * 2x Battery Connectors | ||
+ | |||
+ | Major components are: | ||
+ | * An STM32F106RB Embedded Controller (same as in the [[Embedded_Open_Modular_Architecture/PCMCIA/MicroEngineeringBoard|Micro Engineering Board]] | ||
+ | * A 4-port USB-2 High-speed Hub (e.g. GL850G) | ||
+ | * 12.5Mhz XTAL (for the GL850G) | ||
+ | * Power Management ICs (Buck Converters for 3.8v Lithium to 5.0v; 3.3v LDOs) | ||
+ | * An I2C EEPROM | ||
+ | * An RT2070 or RT3090 USB-compliant MiniPCIe WIFI Module | ||
+ | * An Antennae for the WIFI Module | ||
+ | |||
+ | = Diagram of Tablet Motherboard Layout = | ||
+ | |||
+ | From this diagram, it can be seen that there is very little involved. Like the [http://hardkernel.com/renewal_2011/products/prdt_info.php?g_code=G129689092760&tab_idx=3 Odroid], it's possible to have a product where the connectors and buttons define the size of the PCB more than the ICs and discrete components. In this case, many of the major connectors (such as USB-OTG, HDMI, Micro-SD and Headphones) will already be on the [[Embedded_Open_Modular_Architecture/PCMCIA|EOMA/PCMCIA-compliant]] CPU Card, leaving nothing left for the motherboard than to provide USB2 and Power connectors! An alternative revision is also shown which takes a USB 3G Modem, in PCI-e form-factor. | ||
---- | ---- | ||
[[File:Mini_tablet_motherboard.png|border]] | [[File:Mini_tablet_motherboard.png|border]] | ||
+ | |||
+ | = Diagram of Tablet Construction = | ||
+ | |||
+ | This diagram shows the physical construction of the tablet's components. Critical to achieving a thin tablet, even when allowing for a 5.5mm height PCMCIA CPU Card, is to use an inline PCMCIA header as well as an inline PCI-e connector. If one is used at all (rather than having the PCMCIA CPU card factory-installed) the PCMCIA assembly is shown being attached directly to the tablet's outer casing, rather than being attached to a PCB. Additionally, two batteries are used (in parallel) rather than one, in order to prove a balanced weight distribution to the device. The larger battery sizes, which could even be up to 6mm thickness, potentially allows for cheaper Lithium Polymer batteries to be used - again, reducing the overall cost of the device. | ||
+ | |||
+ | ---- | ||
+ | |||
+ | [[File:Tablet_layout.png|border]] |
Revision as of 16:42, 21 September 2011
Contents
The Tablet Motherboard
Popular by decree, but only successfully-sold when the price is stunningly low yet the feature-set rich, tablets are the "must-have" for all ODMs and OEMs who aspire to a chunk of the large apple pie. Key goals for this motherboard are therefore to be small, slim, low BOM and low-risk development. Thanks also to the modular design, the board is sufficiently simple that it may even be possible to do as a 2-layer PCB, thus reducing costs even further.
Connectors and Components
The connectors required are:
- 1x USB2
- PCMCIA Connector "inline" (signals conforming to EOMA/PCMCIA Standard)
- 5V Power
- 1x PCI Express "inline" (supporting USB Wifi, not PCI-e Wifi, such as RT2070 and RT3090)
- 1x Stereo Speakers and Microphone
- 1x RGB/TTL LCD Output (with LED Backlight)
- 2x Battery Connectors
Major components are:
- An STM32F106RB Embedded Controller (same as in the Micro Engineering Board
- A 4-port USB-2 High-speed Hub (e.g. GL850G)
- 12.5Mhz XTAL (for the GL850G)
- Power Management ICs (Buck Converters for 3.8v Lithium to 5.0v; 3.3v LDOs)
- An I2C EEPROM
- An RT2070 or RT3090 USB-compliant MiniPCIe WIFI Module
- An Antennae for the WIFI Module
Diagram of Tablet Motherboard Layout
From this diagram, it can be seen that there is very little involved. Like the Odroid, it's possible to have a product where the connectors and buttons define the size of the PCB more than the ICs and discrete components. In this case, many of the major connectors (such as USB-OTG, HDMI, Micro-SD and Headphones) will already be on the EOMA/PCMCIA-compliant CPU Card, leaving nothing left for the motherboard than to provide USB2 and Power connectors! An alternative revision is also shown which takes a USB 3G Modem, in PCI-e form-factor.
Diagram of Tablet Construction
This diagram shows the physical construction of the tablet's components. Critical to achieving a thin tablet, even when allowing for a 5.5mm height PCMCIA CPU Card, is to use an inline PCMCIA header as well as an inline PCI-e connector. If one is used at all (rather than having the PCMCIA CPU card factory-installed) the PCMCIA assembly is shown being attached directly to the tablet's outer casing, rather than being attached to a PCB. Additionally, two batteries are used (in parallel) rather than one, in order to prove a balanced weight distribution to the device. The larger battery sizes, which could even be up to 6mm thickness, potentially allows for cheaper Lithium Polymer batteries to be used - again, reducing the overall cost of the device.