Bharat Tablet PC
The Bharat Tablet PC is a low cost tablet being built for distribution in India.
Contents
Overview
The Bharat tablet uses Texas Instruments' Sitara ARM-9 SoC (456 MHz), and provides 256 MiB of DDR2 memory (333 MHz), 128 MiB of SLC NAND Flash soldered to the motherboard, and 2 GB in an internal microSD card.
The one examined had no model number, although Year-2011 is printed in a way to suggest that it is might be the model.
Display
The display size is 7" diagonal w. 16:9 aspect ratio. The resolution is 800x480.
The touchscreen is a single touch resistive touchscreen. It is implemented as a PET film laminated to the front of an unpolished coverglass, which is then attached with adhesive (but not optically laminated) to the front of the LCD module.
There is no internal microphone. There is a single internal speaker.
Connectivity
A 100baseT connection is provided via an RJ-45 jack. No wireless networking is included.
Location/Movement
No location or movement sensing is provided.
Ports
- Two USB type A ports, listed as 2.0 in the specs. The AM1808 only supports a single USB 2.0 port, so one of these is a USB 1.1 port.
- The Sitara SoC supports OTG, although the Bharat tablet doesn't.
- One RJ-45 for 100baseT
- One microSD card, only accessible internally.
- One full size SD card, externally accessible (no cover)
- One 1/8" stereo phono jack for Headphone
- One 1/8" stereo phono jack for Microphone
Power
The Bharat Tablet has a 14.8Wh Li-Ion polymer battery (4Ah @ 3.7V nominal). It is notable that the battery compartment is easily accessible (one screw), and the battery may be replaced without disassembling the unit. The battery size requires is clearly imprinted in the plastic.
The battery is not a smart battery (only a two wire connection), and there is no battery "gas gauge" on the motherboard.
Breakdown
The tablet opens quite easily (just 10 screws, no adhesives), breaking down into a bottom half containing the single PCB and the battery, a bezel, and the sandwich of touchscreen and display.
The screws are all self-tapping, going directly into plastic bosses.
Height
The tablet thickness is roughly 20 mm in the middle. The height stackup is:
| Bezel: 1.6mm | |
| Touchscreen: 0.3mm | |
| Cover glass: 1.4mm | |
| Air Gap: 0.1mm | |
| Display: 5.5mm | |
| Swell gap: 1.3mm | Main PCB: 9.5mm |
| Battery: 8.2mm | |
| Back cover: 1.6mm | |
With the cover (which includes a keyboard), the thickness is 42mm.
Weight
The tablet weight is roughly 470 grams.
| Bezel: | 37g |
| Display & Cover Glass: | 205g |
| Main PCB: | 77g |
| Battery: | 74g |
| Back cover: | 77g |
| Total: | 470g |
A cover with integral keyboard is provided with the tablet. This cover adds another 340g to the weight.
BOM
- BOM for motherboard
- TI Sitara ARM9 SoC
- TLV320AIC3106 Stereo Audio Codec
- SMSC Ethernet Transceiver
- TPS65070 PMIC
- TPS65150 LCD AVDD power supply
Three of the ferrite beads had been soldered down by hand, and there was a handwritten sticker annotating their installation. Hopefully this is a pre-production board..."
