Introduction
One of the biggest issues with MSXI's electrical system was its inconsistency in parts and pinouts. There were at least 3 variations of the CAN controller/transceiver circuit and which SPI bus they were connected to, making debugging difficult. Some used different footprints, while others used different parts. This also made inventory a challenge, as each board had its own very specific set of components.
To increase board consistency and ease debugging, we propose a controller board that consists of shared core components such as the microcontroller, CAN transceiver, and possibly some debug LEDs or IOs. These controller boards would likely use a mezzanine connector to allow breakouts to carrier boards, which should be much simpler.
Key Features
- Allows creation of a debug carrier board to allow self-test of the MCU and CAN
- Simplifies inventory management and software, allowing a single core config for all boards
- Simplifies board debugging - isolates issues to either the controller or carrier boards
- Reduces cost of bringing up backup boards
- Debug headers
Conflicts
- UART/USB? If we use USB, may need serial-to-usb converters on-board (In-car debugging)
- Daisy-chaining power or not (LV Power granularity)
- Hermaphroditic or not (Cost)
- Switching regulator circuit or integrated DC-DC converter (board complexity, cost)
Part Selection
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ARM Cortex-M0 microcontroller
STM32F072RBT6
Includes CAN controller, 51 IOs, 64-LQFP
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TCAN332DR CAN Transceiver
Replacement for the SN65HVD232DR
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External CAN connector
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Molex internal wire-to-board surface mount PCB headers
Molex internal wire-to-board connector housings
Molex internal wire-to-board connector crimp terminals
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http://www.molex.com/molex/products/datasheet.jsp?part=active/0015912055_PCB_HEADERS.xml
http://www.molex.com/molex/products/datasheet.jsp?part=active/0050579405_CRIMP_HOUSINGS.xml
http://www.molex.com/molex/products/datasheet.jsp?part=active/0016020069_CRIMP_TERMINALS.xml
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Molex internal wire-to-board surface mount PCB headers
Molex internal wire-to-board connector housings
Molex internal wire-to-board connector crimp terminals
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http://www.molex.com/molex/products/datasheet.jsp?part=active/0039014050_CRIMP_HOUSINGS.xml
Mini-Fit Jr
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TE internal wire-to-board through hole PCB headers
TE internal wire-to-board surface mount PCB headers
TE internal wire-to-board flat flex cable assembly
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TE internal wire-to-board surface mount PCB headers
TE internal wire-to-board connector housings
TE internal wire-to-board connector crimp terminals
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Low-profile Micro Mate-N-Lok
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Board-to-board IO terminal
Non-hermaphroditic but slightly cheaper
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http://www.te.com/usa-en/product-1565357-6.html#pdp-docs-features
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Board-to-board IO terminal
Mezzostak Hermaphroditic connectors
Samples from FCI are out of stock, order from Digikey
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Board-to-board IO terminal
Samtec LS2 locking hermaphroditic connectors
Samples have been requested
Electrical and mechanical models available
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Board-to-board IO terminal
Samtec LSHM high-speed hermaphroditic terminals
Samples have been requested
Electrical and mechanical models available
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Not on Digikey, will have to find supplier
LSHM-150-02.5-L-DV-A-S-TR
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MCU Schematic Capture
Peripheral Selection
- 51 37 GPIOs
- 2 SPI, 2 I2C, 4 USART, CAN, USB, HDMI-CEC
- 16 Channel 12-bit ADC
- 18 Capacitive Sense Channels
- 2 Analog Comparators
- Serial Wire Debug (SWD)
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