Baseboard for e·MMC memory testing
Baseboard provides all functions for e·MMC memory testing on the system and application level. Baseboard is designed as a universal for different SoM devices and is compatible not only with our Processor module but also with Toradex Colibri PXA, T20, and T30 modules. That’s the reason why are some peripherals (i.e. RTC) contained in the Processor module also in Baseboard. Modularity of final solution allows fast and easy reconfiguration of the memory test bed to different platforms.
Designed peripherals in the Baseboard for memory testing are the following:
· Display 11.6" 1366x768 WSVGA HD LED 40pin Slim SB LVDS – to have visual information about current system status, running processes, errors and testing results. A user should have immediate visual information from the system so it has sufficient resolution and screen size.
· Power source module with current sensing functionality and battery for backup – This block powers all peripherals and Processor module as well. Power module must provide stable and filtered power with sufficient reserves to cover all unexpected current peaks. It has to be able to provide information about the current operating status and react according to the required power management schema. Input voltage of this module is DC voltage from +9 V to +15 V / 3 A. Output voltages are
· +5 V / 400 mA for USB,
· +3.3 V for RS232, LVDS transmitter, e·MMC connector, LCD connector, and Power module via SODIMM connector.
· +3 V battery backup power for RTC and Processor module
· 10/100 Mbit Ethernet bus driver provided via RJ-45 connector – to provide basic connectivity of developed platform is available standard Ethernet interface. Thus, the platform can be connected to LAN and store results of memory test into remote database server or provide them online via a web page or web services. Ethernet also works as the fastest debugging and service interface for Processor module FW updates and debug.
· 4 x USB port – Other necessary or useful peripherals can be connected via USB such as a keyboard, mouse, WiFi module, external HHD or Flash storage drives etc. Due to missing touch-panel on the connected display mouse or external touchpad is the simplest option how to interact with the system and running programs. All 4 USB ports have USB HS standard 2.0 with the total maximum supply current 400 mA.
· Connector for e·MMC card adapter – for easy replacement of tested memory idea of changeable modules was realized. Due to difficult e·MMC part assembling (necessary to use BGA package soldering technology) is this solution ideal for fast and simply connection of tested memory to the testing platform. Connector for e·MMC card adapter provides 10 pin connection for 4 and 8-bit communication up to HS200 mode.
· UART @x RS-232 connectors – One RS-232 interface port is necessary for serial communication with other devices on standard CANNON 9 connector. This interface is used for debug. Implemented OS forwards all debug and system information to this interface. Default setting of this interface is 115200 baud communication speed with 8-bit data width no parity and one stop bit.
· Micro SD card socket – One of the possible boot memories of the Processor module is external SD/MMC memory. Primary boot memory is in the Processor module but module can be configured to use external one. Therefore, Micro SD card socket has to be present on Baseboard to have this option for non-standard and service actions.
· Real Time Clock IC – precise and uninterruptible source of clock is important part of memory testing process especially in long-term testing with power-loss risk. Processor module does not have implemented internal source of clock and uses only system clock generated by processor which is on one hand generated with higher resolution but can be from long term point affected by error. External Real Time Clock circuit solves risk of time information loss.
· Control buttons – at least 2 control buttons have to be available on Baseboard. The first one is for reset function and the second one works as one of the possible wake-up signal sources for the Processor module.
· Backup battery – +3 V backup battery (socket for CR2320) is an integral part of the power control module which supplies RTC and some parts of Processor module during standby mode.
Figure 1: Block diagram of the Baseboard for testing platform
The requirement on the 4 USB connectors in the Baseboard was solved by the implementation of USB 2.0 Hi-Speed Hub Controller USB2514B. This IC provides full USB port power management with individual or ganged power control of each downstream port, fully integrated USB termination with pull-up/pull-down resistors, and can operate from a single external +3.3 V supply source. This chip requires only a few external components such as 24 MHz crystal, power-distribution switches TPS2042BD, and chokes for differential pairs and transient voltage suppressors SRV05-4TCT for ESD protection of the input/output pins.
Figure 2: Top side of the realized Baseboard with the Processor module inserted in the slot