STV0680/680A/680B相机参考设计手册修订版

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"rdm_stv0680-410-500_3-0.pdf" 是STMicroelectronics公司关于数字静态（Dual-Mode）相机芯片组STV0680B (DCA1)与VV6410、6411和6500传感器的参考设计手册的修订版3.0。这份文档适用于采用VV6410（CIF）或VV6500（VGA）传感器的STV0680/680A/680B的任何设计。自修订版2.2以来的重要变更包括： 1. 将音频电路整合到主摄像头的参考设计中，提升了整体功能的集成度。 2. 添加了对VV6411的支持，同时兼容LCC封装的VV6410，扩展了传感器的选择范围。 3. 更新了VV6500和VV6410/6411的管脚布局，移除了未连接的管脚，并调整了一些管脚名称以符合最新的数据手册标准。 4. 引入了OEM闪光灯接口，便于与外部闪光枪的连接，增强了设备的灵活性。 5. 修改了星点符号，可能涉及到电源分布或信号指示的改进。 6. 更新了"设计师故障排查"部分，提供了更详尽的故障诊断和解决指导，帮助开发者更高效地处理设计问题。手册内容概要： 1. 引言：概述了手册的基本信息，包括通用信息和设计目标。 2. 设计细节：可能涵盖了STV0680B芯片组与传感器的接口设计、电源管理、信号处理、图像质量优化等方面。 3. 传感器特性：详细描述了VV6410、6411和6500传感器的特性，包括分辨率、帧率、色彩深度等。 4. 音频集成：解释了如何将音频电路集成到相机设计中，以及相关的音频编码和解码流程。 5. 闪光灯接口设计：阐述了与OEM闪光灯设备的连接方式和控制逻辑。 6. 故障排查：提供了在开发和测试过程中可能出现的问题及其解决方案，有助于快速定位并解决问题。 7. 设计注意事项：列出了设计时应遵循的最佳实践和潜在陷阱，以确保设计的稳定性和可靠性。这份手册对于使用STMicroelectronics的STV0680B芯片组进行数字相机设计的工程师来说是一份重要的参考资料，它不仅更新了硬件设计的细节，还强化了软件和硬件的交互，使得设计更加完善且适应市场的需求。

STV0680B Chipset; Camera Ref. Design Manual, Rev. 3.0, May 2001 STV0680B+VV6410/6411/6500

This version: STMicroelectronics (Imaging Division) internal use only

RDM_STV0680-410-500_contents.fm

3.9 Using two 1.5V batteries

This would require a DC-DC switcher to supply approximately 4.0-5.0v to the PFET Q8 (if fitted), or to the diode D1. But note that

because the STV0680B and SDRAM are always powered in Standby Mode/PC Suspend Mode, this type of supply is only

possible if a DC-DC switcher can be sourced which has a very low self current consumption (i.e. very good switcher efficiency

even at low loads, e.g. load of 300

A). Please contact ST for advice.

3.10 Using a 9v Battery

Using a 9v battery should be possible if the following rules are adhered to:

1. Reference should be made to Section 13., which shows the differences in power supply circuit to the standard Reference

Design.

2. A 5v Voltage regulator U10 with low Quiescent current is required, to keep the input voltage to the sensor regulator within

safe limits (it cannot work direct from a 9v battery). A suitable Torex part has been suggested which includes a Chip Enable

pin, however an alternate implementation could use a Voltage Regulator without a chip enable pin, plus an additional Bipolar

and FET (as per Figure 3) to disable the battery when USB is connected.

3. Observe the value of Low battery sense resistors R10 and R11, the example shown (R10 = 1M, R11 = 220k) assumes that

the battery will lose charge rapidly once 6.75v is reached for a PP3 cell, hence this could be a suitable cut-off point. With six

AAA or AA cells, the design could be used but may require a change to R10 and R11 (for low battery detection) since the

cutoff point at which the battery begins to lose charge rapidly may be different from PP3.

4. For all other aspects of the camera design, no changes are required.

Any battery life example calculations shown elsewhere in this reference design are dependant on the battery voltage and type,

and are hence not applicable for a 9v battery.

Note

: Only limited evaluation work has been done to prove that the implementation shown can work under all circumstances.

3.11 Other power supply considerations

• Ferrites near the USB connector may be required for EMC compliance

STV0680B Chipset; Camera Ref. Design Manual, Rev. 3.0, May 2001 STV0680B+VV6410/6411/6500

This version: STMicroelectronics (Imaging Division) internal use only

RDM_STV0680-410-500_contents.fm

4. Audio Hardware

4.1 Functional descri

tion

4.1.1 Recording

The STV0680B does not have an

analo

ue inputs. However, it is possible to implement a successive approximation Analo

to Di

ital Converter

(

ADC

)

usin

the STV0680B analo

ue output and a discrete comparator.

The si

nal produced b

the Microphone M1 is inputted to the VV6410/6411 or VV6500 sensor pre-amplifier

(

sensor pin AIN

)

. The

pre-amplifier output

(

Sensor pin AOUT

)

is low pass filtered b

R75 and C46, and AC coupled b

C50 to the

(

)

Input of the

comparator U12. R77 and R78 set the DC level of this point to approx. 0.75v. The STV0680B analo

ue output, pin 82

(

DACOUT

)

is the output of an internal 8-bit Di

ital to Analo

ue Converter

(

DAC

)

which has a variable current output, with ran

e 0 - 10mA.

The output is converted to a volta

e b

connectin

a resistor R74 between pin DACOUT and

round. This volta

e is connected to

the

(

)

input of the comparator U12. R82 provides h

steresis to prevent output oscillations, and R83 is re

uired because the

comparator output is open collector.

Hence the (known) voltage derived from the STV0680B DAC compared with the (unknown) AC component of the pre-amplified

Microphone output. An STV0680B pin GPIO4 is used to read the output of the comparator, the status of this GPIO indicates

whether the known DAC output is higher or lower than the analogue input signal derived from the Microphone. STV0680B

firmware tests each of the 8 DAC bits in turn; a technique known as successive approximation. Eight comparisons are required

(one for each bit) for each sample taken.

Sound quality is limited by the 11kHz sample rate.

4.1.2 Playback

Sound pla

back involves amplif

the analo

ue output si

nal from the STV0680B and usin

it to drive a loudspeaker or other

external power amplifier

(

via a headphone socket, for example

)

. The firmware writes appropriate values into the STV0680B DAC

ister in a continuous loop.

4.2 Hardware re

uirements

4.2.1 Recording

picall

the si

nal which is to be recorded ori

inates from a microphone. Some pre-amplification will

enerall

be re

uired and

this can be provided b

the microphone pre-amplifier which is built into the VV6410/6411/6500.

Note that GPIO4 has been used to allow for backward compatabilit

. In a camera usin

STV0680B-001, or in a camera usin

STV0680B-003 without Audio recordin

, this pin should be tied low.

4.2.2 Playback

A power amplifier such as the LM386 is suitable. A simple low-pass filter on the analo

ue output of the STV0680B should be

used.

In order to pla

back sounds which have been recorded on the camera, it will be necessar

to switch off the power amplifier

durin

recordin

or else the successive approximatin

waveform will be heard. This can be achieved b

usin

the GPIO6 pin from

STV0680B to switch off the power to the amplifier

(

usin

a FET Q14

)

or b

usin

an amplifier with an enable si

nal.

The

eneral sound

ualit

pla

ed throu

h the loudspeaker is dependant on the speaker size and

ualit

, so it is recommended

that the OEM evaluates different sizes of speakers before decidin

on the plastics desi

n of the camera.

Note that GPIO6 has been used to allow for backward compatabilit

. In a camera usin

STV0680B-001, or in a camera usin

STV0680B-003 without Audio recordin

, this pin should be tied low.

4.3 Limitations

• If no ima

es are captured, then 16Mbit SDRAM would be able to store approx. 3 minutes 20 seconds of audio, 64Mbit = about

13 minutes.

• The feature is onl

supported on VV6410/6411/6500, but is not supported for VV6444

(

which has no Audio pre-amp

)

• Once sound has been recorded, and/or “custom sounds” have been downloaded and stored in the camera, the specification,

ardin

the number of ima

es which can be stored in SDRAM, is no lon

er valid. More sound means less ima

es.

STV0680B Chipset; Camera Ref. Design Manual, Rev. 3.0, May 2001 STV0680B+VV6410/6411/6500

This version: STMicroelectronics (Imaging Division) internal use only

RDM_STV0680-410-500_contents.fm

5. Other design notes

5.1 STV0680B GPIO pins

Note that GPIO2, 4, 6, 7 have been designated as functions for Audio record/Playback and Flashgun, as summarised in Table 1.

If Audio and Flashgun are not implemented, these GPIO

must

be tied low.

5.2 Sensor interface to STV0680B

STV0680B interprets the embedded codes from sensor data, so there is no need to connect FST from the sensor.

5.3 STV0680B reset

The STV0680B is reset using the RESET input. This only happens on power-up of the STV0680B (i.e. a “cold start”), not on every

wake-up (“warm start”). STV0680B does not have an on-chip Power on Reset module.

Option 1

: Because the sensor Vreg is used to supply the STV0680B, the STV0680B reset must be derived from the PORB pin of

sensor.

Option 2

: Because the sensor is powered down in Standby/PC Suspend mode, the STV0680B reset must be derived from a

separate Power-on Reset chip U8.

5.4 VV6410/6411/6500 reset

The sensor reset input only needs to be supplied with a signal if the sensor is powered on when the camera wakes up from

Standby/PC Suspend mode.

Option 1

: Because the sensor Vreg is always on, the sensor is in SUSPEND mode when the camera is in in Standby/PC Suspend

mode. Hence the sensor should not be reset, the sensor reset input is left floating (i.e. R66 no fit).

Option 2

: The sensor is powered down in Standby/PC Suspend mode and powered up when the camera is waking up. Hence the

sensor reset line is connected to the STV0680B SENSRST

signal, which is driven by firmware during the STV0680B startup

sequence. So fit R66.

5.5 SDRAM

A dual footprint is possible to allow selection of either 16Mbit or 64Mbit SDRAM at the production stage.

Figure 2 : Suggested dual footprint for 64 and 16Mbit SDRAM

• SDRAM de-coupling capacitors C27-33 should be placed close to U4/U5 power supply pins as shown in Section 13.

5.6 Noise considerations

• STV0680B decoupling capacitors C10-C13 should be placed close to STV0680B pins 2, 28, 57, 83.

• To optimise performance, a 4 layer PCB is recommended, incorporating a ground and power plane, separated back to the

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