Tiny v2

The complete re-design of the popular Tiny autopilot was done on October 9, 2007. The new design is not a bug-fix as no known flaws exist with the current 0.99 and 1.1 versions, so the redesign is performance, easy to use and easy to assemble-oriented !

Hardware Revision History

Version #	Release Date	Release Notes
v2.11	12/2007	Bug fix : GPS Reset pin protection (D2)
v2.1	10/2007	3.3V regulator type changed, power switch type changed, connectivity improved
v2.0	06/2007	Initial release of Tiny v2

Features

Single LPC2148 MCU
8 Analog input channels 0V - 3.3V (2 channels with optional on-board resistor bridge)
1 3.3V TTL UART (5V tolerant)
8 PWM outputs
1 R/C receiver PPM frame input
1 SPI bus
1 I²C bus
1 USB (client)
Integrated GPS receiver and patch antenna (4Hz update)
5V/2.5A switching power supply & 3.3V/1A linear regulator
3 status LEDs with attached test point
?? grams
70.8 x 40mm (smaller then a banking card)
2 layers PCB design, 0603 components

Tiny v2.1 3D top view (18mm GPS antenna)
Tiny v2.1 3D bottom view
Tiny v2.1 top side view (13mm GPS antenna)
Tiny v2.1 bottom side view

The Tiny v2.1 autopilot uses a single Philips LPC2148 ARM7 based microcontroller. The ARM7 is a low-power 32-bit RISC processor core and the Philips LPC2148 has 512KB on-chip Flash ROM, 40KB RAM and can be clocked at 60MHz.

Although critical control code such as the R/C interface and servo output are well segregated in Paparazzi software and well protected from interference from flaws in the stability/navigation/comm/payload code, great care must be taken when experimenting with new software as some errors can cause a the processor to halt or stall for extended periods causing total loss of control.

Feature additions : Tiny 2.1 vs Tiny 1.1

Hardware flow control on the modem

The LPC has one "full-featured" serial port and one basic serial port.

Tiny v1.1 had the full-featured port hard-wired to the GPS in order to leave the basic port open for initial bootloader programming.

Tiny v2.1 exchange these ports and use the GPS Reset signal to "disconnect" the GPS for the one-time bootloader programming. Hardware flow control on the modem is now possible.

5V switching power supply

The Texas Instruments PTH08080WAH switching 5V/2.25A integrated power supply module greatly simplify manufacturing, reduce costs, and improve performance.

Tiny v2.1 have a voltage input range of 6-16V and enough 5V power for large servos and high-power modems and video systems.

3.3V linear regulator

Tiny v2.1 use a 1A regulator for 5V to 3.3V conversion in a SOT223 standard pinout package which is capable of providing plenty of power to modems or other devices.

Tests have shown that any device with irregular power consumption can cause significant voltage fluctuations on the critical 3.3V bus.

Users are advised to use a separate regulator as needed for such devices.

Video/payload power switch.

The TPS1100 transistor used on the Tiny v1.1 design has proven extremely useful but is intended for high-speed power switching of motor controllers and occupies a 5mm x 6mm space (SOIC-8).

The replacement on the new Tiny v2.1 is a current-limiting switch TPS2051B intended for peripheral power control and should protect the 5V supply from voltage sags during the power-up of high capacitance peripherals as well as allow the 5V supply to continue working in the event of a complete short-circuit in the payload.

TPS2051BDBVR Single 500mA (1A limited) switch in a 3mm x 3mm SOT23-5 package

GPS ground plane and antenna

The 13mm antenna on previous Tiny v1.1 proved to be an unworthy exchange of performance for weight. Crude parking-lot tests showed an approximate 3dBi loss (as expected from the data sheets), but the narrow bandwidth of the small antenna made it more sensitive to de-tuning from nearby components in the aircraft. Flight performance was acceptable but poor climb rate calculations were observed with the smaller antenna. Tiny 1.1 users are advised to fit a 20mm antenna.

Tiny v2.1 use a 18mm x 4mm antenna (20mm x 4mm is possible but no more available) and feature 30% more ground plane area (40 x 40mm).

GPS Reset

Occasionally the GPS fails to boot properly, displays very poor S/N ratios, and fails to obtain a valid fix. This may be caused by a slow power-up of the 5V or 3V regulators, or by some unusual EMI that is only present at boot. Usually a simple power cycle will correct the problem but occasionally the receiver seems to use the backup battery to retain the bad state.

On the Tiny v2.1 design GPS reset is connected to a GPIO pin on the MCU and allow the operator to reset the GPS as needed.

Headers

Tiny v2.1 feature revised header layouts on all peripherals.

The modem header have CTS/RTS/DTR and both 5V and 3.3V supplies.(3.3V is shared with LPC and ADC channels - use with caution and only with very low power modems like the 10mW Xbee).
The Tiny v1.1 button is removed and it's function is combined on the USB header along with a LED trigger so that indicator, button, and USB can be remotely mounted.
Vertical Infrared (1 ADC) with 3.3v supply
Horizontal Infrared (2 ADC) with 3.3v supply
2 general purpose ADC with both 3.3v and 5v supplies
2 general purpose ADC with optional on-board resistor bridge and both 3.3v and 5v supplies
Two axis Camera control with two servo signal, vdo switch control, vdo power switch and both 5V and 3.3V supplies
SPI bus with 3.3V supply
I2C bus with both 5V and 3V supplies

Leds & testpoints

3 status LEDs with attached test point available on Tiny v2.1 design (instead 2 on Tiny v1.1)

Components size

Many users (not only beginners) don't really think that 0402 components on Tiny v1.1 is a great saving from any viewpoint. Even if one saves a little space by using these components, there must still be enough room around to solder it by hand with a soldering iron.

Tiny v2.1 use 0603 components, the assembly will be a bit more friendly to everyone.

Layers amount

Tiny v2.1 2 Layer design (instead 4 Layers on Tiny v1.1) should simplify manufacturing and reduce costs.

Architecture

Pinout

Pins Name and Type are specified with respect to the Autopilot Board

**SERIAL**
Pin #	Name	Type	Description	Suggested Color
1	GND	PWR	common ground	Black
2	+5V	PWR	5V Rail from Tiny	Orange
3	+3.3V	PWR	3.3V Rail from Tiny	Red
4	DTR
5	CTS
6	RTS
7	RXD1	IN	UART1 Serial Input (3.3V level, 5V Tolerant)	Green
8	TXD1	OUT	UART1 Serial Output (3.3V level)	Blue

**SPI**
Pin #	Name	Type	Description	Suggested Color
1	GND	PWR	common ground	Black
2	+3.3V	PWR	3.3V Rail from Tiny	Red
3	SSEL	IN	SSP Slave Select. Selects the SSP interface as a slave (SSEL1)	Braun
4	MOSI	I/O	SPI1 Master Out Slave In. Data output from master or data input to slave	Grey
5	MISO	I/O	SPI1 Master In Slave Out. Data input to master or data output from slave	Green
6	DRDY	IN	External interrupt 0 input (EINT0)	Purple
7	SCK	I/O	SPI0 Serial clock. Clock output from master or input to slave	Yellow

**PPM**
Pin #	Name	Type	Description	Suggested Color
1	GND	PWR	common ground	Black
2	+5v	PWR	5V Rail from Tiny to R/C receiver supply	Orange
3	PPM_IN	IN	PPM Stream from R/C Receiver (5V tolerant)	White
4	SERV_RST	OUT	external PPM decoder reset (Note 1)
5	SERV_CLK	OUT	external PPM decoder clock (Note 1)

Note 1 : Used only if servos are connected to the R/C receiver

**USB**
Pin #	Name	Type	Description	Suggested Color
1	GND	PWR	common ground	Black
2	+3.3V	PWR	3.3V Rail from Tiny	Red
3	USB+	I/O	USB bidirectional D+ line	Green
4	USB-	I/O	USB bidirectional D- line	White
5	VBUS	IN	Indicates the presence of USB bus power (P0.23) (5V level)	Orange
6	BUTTON	IN	External Button (+3.3v pullup)
7	LED3	OUT	GPIO (LED #3 command)
8	ADC_7	IN	Analog to Digital Converter Input #7

**IRV**
Pin #	Name	Type	Description	Suggested Color
1	GND	PWR	common ground	Black
2	+3.3V	PWR	3.3V Rail from Tiny	Red
3	IRV	IN	Vertical IR Sensor signal (Analog to Digital Converter Input #0)	Purple

**IRH**
Pin #	Name	Type	Description	Suggested Color
1	GND	PWR	common ground	Black
2	+3.3V	PWR	3.3V Rail from Tiny	Red
3	IRH_2	IN	Horizontal IR Sensor signal axis 2 (Analog to Digital Converter Input #2)	Grey
4	IRH_1	IN	Horizontal IR Sensor signal axis 1 (Analog to Digital Converter Input #1)	Braun

**ADC1**
Pin #	Name	Type	Description	Suggested Color
1	GND	PWR	common ground	Black
2	+5v	PWR	5V Rail from Tiny	Orange
3	+3.3V	PWR	3.3V Rail from Tiny	Red
4	ADC_4	IN	Analog to Digital Converter Input #4
5	ADC_3	IN	Analog to Digital Converter Input #3

**ADC2**
Pin #	Name	Type	Description	Suggested Color
1	GND	PWR	common ground	Black
2	+5v	PWR	5V Rail from Tiny	Orange
3	+3.3V	PWR	3.3V Rail from Tiny	Red
4	ADC_6	IN	Analog to Digital Converter Input #6 (Maximum input level can be selected with R12 & R14 values)
5	ADC_5	IN	Analog to Digital Converter Input #5 (Maximum input level can be selected with R13 & R15 values)

**DOWNLOAD**
Pin #	Name	Type	Description	Suggested Color
1	GND	PWR	common ground	Black
2	+5v	PWR	5V Rail from Tiny	Orange
3	+3.3V	PWR	3.3V Rail from Tiny	Red
4	BOOT	IN	In-Circuit Serial Programming (ISP) enable (P0.14, +3.3v pullup) (Note 2)
5	GPS_RESET	IN	leave unconnected, hold this pin low only for bootloader programming
6	TXD0	OUT	UART0 Serial Output (shared with GPS receiver)	Blue
7	RXD0	IN	UART0 Serial Input (shared with GPS receiver)	Green

Note 2 : Holding this pin low for at least 3mS after a RESET (or power up) instructs the controller to enter programming mode.

**I2C**
Pin #	Name	Type	Description	Suggested Color
1	GND	PWR	common ground	Black
2	+5V	PWR	5V Rail from Tiny	Orange
3	+3.3V	PWR	3.3V Rail from Tiny	Red
4	SDA	I/O	I2C bus Serial DAta
5	SCL	I/O	I2C bus Serial CLock

**CAM**
Pin #	Name	Type	Description	Suggested Color
1	GND	PWR	common ground	Black
2	+5V	PWR	5V Rail from Tiny	Orange
3	+3.3V	PWR	3.3V Rail from Tiny	Red
4	CAM_SW	OUT	video source/payload selection signal
5	SRV_1	OUT	Servo PWM signal #1
6	SRV_5	OUT	Servo PWM signal #5
7	AUX	PWR	video/payload switchable 5V power suply