4 layers88.9 × 79.4 mm
Link
oats-center/avena-rs
Avena On The Road: Bringing pavement health data to your fingertips
170 parts3
2 layers66 × 65 mm
EL-210-MOD
suikan4github/EL-210-MOD3Alternative circuit for SHARP EL-210 calculator
- Size
- 66 × 65 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 36
- Nets
- 82
- Pads
- 186
- Tracks, vias
- 341, 52
- Pours
- 3
- Routed
- Yes
- KiCad
- KiCad 6 (file 20211014)
- Created
- 12 Nov 2022
- Updated
- 23 Feb 2024
Overview
EL-210-MOD is an open-source printed circuit board by suikan4github, from the suikan4github/EL-210-MOD repository on GitHub, published under the MIT licence. It is a 2-layer board of 66 × 65 mm with 36 parts on 82 nets, routed with 341 tracks and 52 vias.
It is built around the STM32G0B1KET6, MAX6934AQH+D and TLV61046ADBV, with the TPS613221ADBV and MAX4719EUB+ among its other parts. Its parts include 11 capacitors, 6 ICs, 5 resistors, 3 connectors and 2 diodes. It belongs with the STM32 boards of this library.
Main components
5
STM32G0B1KET6
LQFP-32(7x7)-40℃~+85℃ 1.7V~3.6V 12bit 12bit 144KB 30 32 Bit 512KB 64MHz ARM Cortex-M0+ Built-in+External FLASH LQFP-32(7x7) Microcontrollers (MCU/MPU/SOC) ROHSSTMicroelectronicsMicrocontrollers (MCU/MPU/SOC)MAX6934AQH+D
PLCC-44(16.6x16.6)PWM dimming、Internal reset function、Cascadable function PLCC-44(16.6x16.6) VFD Drivers ROHSMaxim Integrated (Analog Devices)Digital Tube Drivers
TLV61046ADBV
SOT-23-6-40℃~+125℃@(TJ) 1 1.05MHz 1.8V~5.5V 110uA 3.3V~28V Adjustable Boost Boost Built-in No Overcurrent Protection、Light load efficient mode、Load disconnect SOT-23-6 DC-DC Converters ROHSTexas InstrumentsDC-DC Converters
TPS613221ADBV
SOT-23-5-40℃~+125℃@(TJ) 1 1.6MHz 3.3V 6.5uA 900mV~5.5V Boost Boost Built-in Fixed Yes SOT-23-5 DC-DC Converters ROHSTexas InstrumentsDC-DC Converters
MAX4719EUB+
MSOP-10-40℃~+85℃ 1.8V~5.5V 100ns 2 20pF 20Ω 2:1 300MHz 50ns MSOP-10 Analog Switches, Multiplexers ROHSMaxim Integrated (Analog Devices)Analog Switches, Multiplexers
README
README.mdEL-210-MOD
Alternative circuit for SHARP EL-210/EL-215 calculator
Description
This is a circuit/board design for the alternate PCB for the SHARP EL-210/215 calculators. SHARP EL-210 series are manufactured around early 1980th. By using this alternate PCB, you can program any program as firmware of this classic VFD calculator.
There is an dedicated RPN firmware is located in the rpn2026 project.
To make your own RPN calculator, user must follow the procedure :
- Take the main board of the EL-210 out.
- Move the VFD from the old board to this board.
- Set this board into the EL-210 calculator.
- Program the board with the appropriate RPN firmware.
Circuit Design
You can found additional design resources :
VFD specification
The VFD is 9-ST-20, manufactured by Futaba. The specification is not disclosed. Pin assignment has been investigated by LI2026ODP project.
- Anode voltage : 25V
- Heater voltage : 2.5v (Differential square wave drive), 21mA.
- Grid cutoff : 4V
Heater driver
The heater must be driven by differential alternate current. This is required to make the flat brightness between right-end and left-end of the VFD. If you drive the heater by DC, the voltage slope of the heater will make the slop of the brightness.
The analog switch provide the low voltage drop out current switching. The timing is made by MCU timer.
Grid bias
The grid bias is required 4. Because the balanced drive of the heater makes 1.65V grid bias, we need only 2.5V more.
Key matrix
The key matrix has been investigated by also LI2026ODP project.
The EL-21x series key matrix doesn't have any protection diode. Thus, to prevent the signal shortage, the GPIO pins for the key matrix have to be configured :
- Row : Open Drain output.
- Col : Input with pull-up register.
To check the button pushed, output the "L" from the Row. If the Column get "L", the button is pushed.
| Row | Column 0 | Column 1 | Column 2 |
|---|---|---|---|
| 0 | CE | X->M | 0 |
| 1 | 7 | 4 | |
| 2 | CM | 8 | 1 |
| 3 | . | 5 | % |
| 4 | + | RM | 2 |
| 5 | C | 9 | = |
| 6 | / | M- | |
| 7 | * | 6 | 3 |
| 8 | - | M+ | sqrt |
24V
To supply the 24V to VFD, set EN24 signal to "H".
Caution
In the case you order the PCB to a board manufacturer, you must specify the PCB thinness as 1.0mm. The standard 1.3mm is too thick.
Known Problems
The Grid bias is not deep as expected. It is -0.9V while expected -2.5v. It is left untouched because it is not problematic.
Gallery
Parts
36| Qty | Value | Footprint | References |
|---|---|---|---|
| 7 | 0.1u | Capacitor_SMD:C_0603_1608Metric_Pad1.08x0.95mm_HandSolder | C2, C3, C4, C7, C8, C9, C10 |
| 3 | 18 | Resistor_SMD:R_0603_1608Metric_Pad0.98x0.95mm_HandSolder | R1, R2, R3 |
| 3 | hole_2.8mm | hole:hole_2.8mm | H4, H5, H6 |
| 2 | 1u | Capacitor_SMD:C_0603_1608Metric_Pad1.08x0.95mm_HandSolder | C1, C5 |
| 2 | D_Schottky | Diode_SMD:D_0603_1608Metric_Pad1.05x0.95mm_HandSolder | D1, D2 |
| 2 | hole_1.9mm | hole:hole_1.8mm | H3, H7 |
| 2 | hole_2.0mm | hole:hole_2.0mm | H1, H2 |
| 1 | 10u | Capacitor_SMD:CP_Elec_6.3x3.9 | C11 |
| 1 | 10uH | project_lib:LQH5BPN100M38L | L2 |
| 1 | 2.15k | Resistor_SMD:R_0603_1608Metric_Pad0.98x0.95mm_HandSolder | R5 |
| 1 | 22u | Capacitor_SMD:CP_Elec_4x3.9 | C6 |
| 1 | 4.7uH | project_lib:LQH5BPN100M38L | L1 |
| 1 | 61.9k | Resistor_SMD:R_0603_1608Metric_Pad0.98x0.95mm_HandSolder | R4 |
| 1 | 9-ST-20 | 9-ST-20:9-ST-20 | U1 |
| 1 | Conn_01x02 | Connector_PinHeader_2.54mm:PinHeader_1x02_P2.54mm_Vertical | J2 |
| 1 | Conn_01x05 | Connector_PinHeader_2.54mm:PinHeader_1x05_P2.54mm_Horizontal | J1 |
| 1 | EL-210-KEY | EL-210-KEY:EL-210-KEY | P1 |
| 1 | MAX4719EUB+ | Package_SO:MSOP-10_3x3mm_P0.5mm | U5 |
| 1 | MAX6934AQH+D | plcc44_hs:PLCC44_handsoldering | U3 |
| 1 | STM32G0B1KET6 | Package_QFP:LQFP-32_7x7mm_P0.8mm | U2 |
| 1 | TLV61046ADB | Package_TO_SOT_SMD:SOT-23-6 | U6 |
| 1 | TPS613221ADBV | Package_TO_SOT_SMD:SOT-23-5 | U4 |
Questions
How big is the EL-210-MOD PCB?
It measures 66 × 65 mm and has 2 copper layers, 1.6 mm thick.
What parts does the EL-210-MOD use?
36 parts, built around the STM32G0B1KET6, MAX6934AQH+D, TLV61046ADBV and TPS613221ADBV. The full list of its parts is on this page, with links to each part's symbol and footprint where PCBKit's library has them.
Where can I download the EL-210-MOD KiCad files?
From the suikan4github/EL-210-MOD repository on GitHub, at the commit this page was made from: the board is EL-210-MOD.kicad_pcb and its schematic EL-210-MOD.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the EL-210-MOD design in my own project?
Its repository publishes it under the MIT licence: you may reuse it on that licence's terms (keep the author's notice, and for a copyleft licence share your changes alike).
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