Colibri Carrier and Analog to Digital Converter Manual

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3 Table of contents Introduction 4 CADC board connector pin-out 5 SPI communication 11 I 2 C communication 12 Digital communication 13 Analog inputs 14 CADC Service board description 14 Appendix A. CADC board performance test 16 CADC board specification 21 3

4 Introduction This is a manual for a carrier and analog to digital converter for a Toradex Colibri module CADC. The board CADC is a universal carrier for the Colibri module that allows its operation without any additional supporting hardware as a data acquisition unit. On CADC Colibri becomes a computer with a 12 bit 2 x 12 channel (single ended) analog to digital converter. The CADC board also contains a power supply and Ethernet magnetics, thus in a combination with Colibri it is an independent data acquisition computer with significant storage space (micro SD card) available on an Ethernet network. The CADC board provides: Two 12 channel single ended analog to digital converters with 12 bit resolution (2 x ADuC7026) Very efficient power supply for the Colibri and for its own operation (allows 4 to 17 VDC input voltage, total power consumption in operation is under 1.6 W typically) Digital to analog video signal VGA converter (6 bit) Micro SD card holder Connection to a service board Ethernet magnetic module allows Colibri to operate with common network devices All in a very small package - length: 76 mm x width: 48 mm x height: 10 mm, weight 34 grams (including installed Colibri module) Analog1 (J6) ADC1 I 2 C Analog2 (J7) ADC2 Power (J1) Power supply JTAG (J5) SPI SPI RAM SD card conn. Ethernet (J8) VGA DAC SODIMM conn. Service (J6) Figure 1. Simplified CADC board block diagram. Blue lines illustrate I 2 C communication and green line SPI communication. 4

5 Additional module - service board allows connection of peripheral devices to Colibri. Service board is connected with CADC board by 40 pin FPC cable and allows access to the following: Two USB ports (client and host) PS2 keyboard and mouse VGA monitor Two RS232 interfaces JTAG interface to both A/D microcontrollers Figure 2. CADC service board. CADC board connector pin-out J1 Power and digital signals connector J3 Service board connection J5 - JTAG connector J6, J7 ADC input connector J8 Ethernet connector Figure 3. Connectors located on bottom side of the CADC board. 5

6 Figure 4. Connectors on the top side of the CADC board. Figure 5. Major dimensions of the CADC board in millimeters. 6

7 J1 Power supply, etc. A 24 pin connector with zero insertion force (ZIF) for a flat cable with 0.5 mm pitch. Pin # Functionality 1 Vcc 2 Vcc 3 Vcc 4 Vcc 5 Vcc 6 Vcc 7 Vcc 8 Vcc 9 GND 10 GND 11 GND 12 GND 13 GND 14 GND 15 GND 16 GND 17 ADuC Reset 18 IRQ0 19 GPIO1 20 GPIO2 21 GPIO3 22 Sync1 23 Sync2 24 Colibri Reset 7

8 J3 Service board connection A 40 pin ZIF connector for a flat cable with 0.5 mm pitch. Pin # Functionality 1 USBH_P 2 USBH_N 3 USBC_P 4 USBC_N 5 USBC_DET 6 VGA_GND 7 VGA_GND 8 VGA VSYNC 9 VGA HSYNC 10 VGA BLUE 11 VGA GREEN 12 VGA RED 13 ADuC Reset 14 Colibri Reset 15 GND 16 USB_EN 17 USB_OC 18 Vcc V 20 GND 21 UART_BT_TXD 22 UART_BT_RXD 23 UART_BT_RTS 24 UART_BT_CTS 25 GND 26 GND 27 GND 28 GND 29 PS2_SCL1 30 PS2_SDA1 31 PS2_SCL2 32 PS2_SDA2 33 UART_FF_RI Pin # Functionality 34 UART_FF_TXD 35 UART_FF_RXD 36 UART_FF_DCD 37 UART_FF_DSR 38 UART_FF_RTS 39 UART_FF_CTS 40 UART_FF_DTR 8

9 J5 - JTAG connector A 24 pin ZIF connector for a flat cable with 0.5 mm pitch. Pin # Functionality 1 TRST_2 2 GND 3 TDO_2 4 GND 5 TCK_2 6 GND 7 BM_2 8 GND 9 TDI_2 10 GND 11 TMS_ V V 14 TMS_1 15 GND 16 TDI_1 17 GND 18 BM_1 19 GND 20 TCK_1 21 GND 22 TDO_1 23 GND 24 TRST_1 9

10 J6, J7 ADC input connector A 45 pin ZIF connector for a flat cable with 0.5 mm pitch. J6 provides analog signals to ADC1 (right chip in Figure 3), which is accessed for programming through JTAG signals TMS_1, TDI_1, BM_1, TCK_1, TDO_1, and TRST_1 (see J5 pinout); and J7 correspondingly provides analog signals to ADC2 (left chip in Figure 3) with corresponding JTAG signals: TMS_2, TDI_2, BM_2, TCK_2, TDO_2, and TRST_2. Pin # Functionality 1 IRQ1 2 I2C_SDA 3 I2C_SCL 4 P4.2 5 P4.3 6 P4.4 7 P4.5 8 Timer0 9 GPIO5 10 GPIO4 11 GND 12 GND 13 Vcc 14 Vcc 15 Vcc 16 Vcc 17 Vcc V 19 GND 20 GND 21 ADC_NEG 22 GND 23 ADC_11 Pin # Functionality 24 GND 25 ADC_0 26 GND 27 ADC_1 28 GND 29 ADC_2 30 GND 31 ADC_3 32 GND 33 ADC_4 34 GND 35 ADC_5 36 GND 37 ADC_6 38 GND 39 ADC_7 40 GND 41 ADC_8 42 GND 43 ADC_9 44 GND 45 ADC_10 J8 Ethernet connector A 5 pin ZIF connector for a flat cable with 1 mm pitch. Pin # Functionality 1 RX+ 2 RX- 3 ETH_GND 4 TX- 5 TX+ 10

11 SPI communication SPI 4-wire bus is used for communication between ADC chips and Colibri units. For that purpose pins 86 (CSL), 88 (CLK), 90 (RxD), and 92 (TxD) of 200-pin SODIMM Colibri connector are connected to pins 51 (CSL), 58 (CLK), 52 (MOSI), and 57 (MISO) of both ADuC7026 microcontrollers [1]. If Colibri module is a slave and ADC master(s) SPI configuration is implemented than RxD should be connected to MOSI and TxD to MISO pins (Table 1). Colibri pin functions are shown according to Colibri migration guide for PXA320 [2]. Table 1 SODIMM pin Colibri func. ADC pin ADC func. 86 CSL 51 (P1.7) SPI_CSL 88 CLK 58 (P1.4) SPI_CLK 90 TxD 57 (P1.5) SPI_MISO 92 RxD 52 (P1.6) SPI_MOSI 169 GPIO46 29 (P3.0) GPIO (HOLD SPI RAM) If the Colibri unit is programmed as SPI master and ADC microcontrollers are programmed as slaves, than RxD should be connected to MISO and TxD to MOSI pins (Table 2). Table 2 SODIMM pin Colibri func. ADC pin ADC func. 86 CSL 51 (P1.7) SPI_CSL 88 CLK 58 (P1.4) SPI_CLK 90 TxD 52 (P1.6) SPI_MOSI 92 RxD 57 (P1.5) SPI_MISO 169 GPIO46 29 (P3.0) GPIO (HOLD SPI RAM) Master/Slave configuration can be easily set by connecting four pads shown in Figure 6 either in vertical pairs (red lines) for Colibri to work as a slave and ADC master(s) configuration, or in horizontal pairs (blue lines) for Colibri master ADC slaves configuration. 32kB SPI RAM (23K256 by Microchip [3]) is connected to the SPI bus. It can be used as a SPI buffer during data transmission between ADCs and Colibri. HOLD line of SPI RAM is controlled either by Colibri or by one of the ADC chips: pin 168 of SODIMM connector (GPIO46 of Colibri unit) and pins 29 (P3.0) of both ADC microcontrollers are also connected. Keeping HOLD high effectively disables SPI RAM. The SPI line is intended for internal communication only, so it is not available on any of the board connectors. 11

12 Figure 6. Location of pads for SPI configuration. I 2 C communication 2-wire I 2 C line can be used for communication between Colibri unit, ADC microcontrollers and I 2 C external devices. For that purpose pins 194 (SDA) and 196 (SCL) of the Colibri SODIMM connector are connected to pins 61 (P1.1 SDA) and 62 (P1.0 SCL) of both ADuC7026 microcontrollers (Table 3). Both lines have 4.7 kω resistors to pull them up to 3.3V, so additional pull up resistors are not needed for external I 2 C devices. I 2 C lines are accessible through both J6 and J7 analog signal connectors (i.e. pins 2 and 3 of J6 and J7 are internally connected). A user should keep in mind that microcontroller pins P1.0 and P1.1 share many functions, so it is the user s responsibility to program their function properly for I 2 C communication. Table 3 J6/J7 pin Func. SODIMM pin Colibri func. ADC pin ADC func. 2 SDA 194 I2C_SDA 61 (P1.1) SDA 3 SCL 196 I2C_SCL 62 (P1.0) SCL 12

13 Digital communication A set of lines for digital communication are implemented in the CADC board. They can be divided into three groups according to function: 1) 3 external digital signals (e.g. synchronization signals) acquired by Colibri and/or ADC microcontrollers and 3 general purpose inputs/outputs (GPIOs) to/from Colibri through J1- (power supply, etc.) connector 2) 4 GPIOs to/from each of two ADC microcontrollers (J6, J7 ADC input - connectors) 3) 2 handshaking lines connecting Colibri GPIOs (pins 176, 180 of SODIMM) with both ADC GPIOs (pins 56 (P4.1), 55 (P4.0)) There are two additional digital lines on connector J1, which allow user to reset Colibri computer and/or both ADC microcontrollers by putting them to ground. Colibri GPIOs There are six digital lines intended for communication with the CADC board through power supply connector J1. If lines are connected to pins of the ADC microcontrollers, both microcontrollers are connected. Digital lines are summarized in Table 4. Table 4 J1 pin Func. SODIMM pin Colibri func. ADC pin ADC func. 18 IRQ0 NC 40 (P0.4) IRQ0 19 GPIO1 170 GPIO47 NC 20 GPIO2 172 GPIO48 NC 21 GPIO3 174 GPIO25 NC 22 Sync1 154 GPIO89 19 (P4.7) GPIO 23 Sync2 156 GPIO90 18 (P4.6) GPIO In addition to the lines going through J1 there are two lines connecting Colibri to both J6 and J7 connectors (corresponding pins of J6 and J7 are internally connected). They allow users to send/receive control signals to/from Colibri unit directly to external devices, while analog signals are acquired through the same connectors. Table 5 provides information necessary for accessing GPIOs. Table 5 J6/J7 pins Func. SODIMM pin Colibri func. 9 GPIO5 135 GPIO95 10 GPIO4 133 GPIO94 ADC GPIOs Four GPIOs from each ADC microcontrollers are connected to corresponding pins of J6 and J7. They can be used to generate control signals for external devices and/or acquire digital information about their states. Additionally there are separate lines connecting IRQ1 pins of microcontrollers to corresponding connectors. They allow generating interrupts for low-latency 13

14 data processing (e.g. microcontroller(s) can be used for pulse counting, digital encoder reading, etc.) Table 6 summarizes these digital signals. Table 6 J6 pin ADC1 pin J7 pin ADC2 pin ADC func (P0.5) 1 41 (P0.5) IRQ (P4.2) 4 63 (P4.2) GPIO 5 64 (P4.3) 5 64 (P4.3) GPIO 6 65 (P4.4) 6 65 (P4.4) GPIO 7 66 (P4.5) 7 66 (P4.5) GPIO Handshaking lines Two digital lines are dedicated specifically for exchanging digital information between Colibri and ADC microcontrollers. They are not connected to any connector but rather are intended for handshaking between devices. These Colibri pins are connected to both ADC corresponding pins, i.e. these lines also can be used for communication between ADC microcontrollers. Table 7 provides information about these lines. Table 7 ADC1/2 pin Func. SODIMM pin Colibri func. 55 (P4.0) Sig2 180 GPIO41 56 (P4.1) Sig1 176 GPIO24 Analog inputs The CADC board uses two 12-bit ADuC7026 microcontrollers for analog-to-digital conversion. Each analog input is loaded on a 1K pull-down resistor. Resistor value is chosen to minimize noise level and channel-to-channel cross-talk. According to the ADuC7026 specification range of analog signal input is 0 2.5V. Internal source of reference voltage of 2.5VDC is used. Single-ended mode is implemented. Analog channel 12 of each ADC microcontroller can be programmatically connected to the internal temperature sensor with calibration curve provided in the ADuC7026 manual. CADC Service board description The service board, see Figure 2, allows connection of various peripherals to the CADC and Colibri itself. Its function is to help the CADC/Colibri prepare for autonomous operation. The service board is connected to the CADC via two flat cable connectors Service and JTAG connector (corresponding to J3 and J5 connectors on CADC). The service board does not require external power supply. The CADC service board allows connection to the following: PS2 keyboard and mouse VGA video USB host and USB client 14

15 Two RS-232 channels (service board contains two UART to RS-232 converters) Two JTAG connectors to two ADC chips on the CADC Vcc, 3.3V, 5V, GND, and reset lines to microcontrollers and Colibri (see Figure 7 and Table 8) Figure 7. Location of power and reset lines connector on service board. Table 8 Pin # Functionality 1 USB_OC 1) 2 COLIBRI_RESET 3 USB_EN 1) 4 ADC_RESET 5 Vcc 6 NC 7 5V 8 NC 9 GND 10 NC V 12 NC 13 NC 14 NC 15 NC 16 NC 1) For debugging purpose only. Other connectors located on the board (SV2-5) are for internal use only. 15

16 J8 to RJ-45 adapter. The flat cable from connector J8 can be connected to the adapter shown in Figure 8 to allow connection to a regular RJ-45 Ethernet connector. Figure 8. Flat cable to RJ-45 adapter. References 1. ADuC7026 analog microcontroller manual. 2. Colibri migration guide K256 SPI RAM manual. Appendix A. CADC board performance tests. In order to evaluate the analog to digital convertor performance in operation with the Colibri module, two tests were evaluated: low bit noise test and channels cross-talk test. Low-bit noise test To measure low-bit noise 2 input channels (counting from ADC0 to ADC11) on both chips were driven by two 1.5 VDC batteries. The first chip has 5 kω load (pull-down) resistor and the second has 1 kω load resistor on corresponding analog inputs. Channels are switched in continuous scans from channel 0 to 11 on both ADC microcontrollers simultaneously. Time between switching channels is 10 µs. Scans are repeated with the frequency 1 khz. The data were recorded during 7 minutes. The following plots show time dependence of two channel counts (Figs. A1 and A2) and corresponding histograms of count distribution (Figs. A3 and A4). Titles on Figures A3 and A4 indicated signal standard deviation. Conversion of counts to input voltage can be done according to the following formula: V = (C/4096)*2.5, where 2.5 V is the internal reference voltage. Signal distributions (Fig. A3, A4) are close to Gaussian with STD~1.0. The difference of STD between two loads is very small, so resistor value is not critical. It is hard to conclude that the difference of noise levels is due to higher or lower current (load resistor value). Count spreading 16

17 is slightly higher than that shown in the ADuC7026 manual. It is conceivable that the ADuC27026 chip manufacturer s results in the manual are for a case without channel multiplexing. Switching channels can easily add some noise, cross-talk, thus increase the signal STD R=5K ADC counts (1.5VDC) Time, s 2224 Figure A1. Analog input with 5K load resistor. R=1K ADC counts (1.5VDC) Time, s Figure A2. Analog input with 1K load. 17

18 15 x 104 R=5K, STD = N ADC counts (1.5VDC) Figure A3. Distribution of ADC counts with R=5K. Standard deviation is x 104 R=1K, STD = N ADC counts (1.5VDC) Figure A4. Distribution of ADC counts with R=1K. Standard deviation is

19 Cross-talk test To measure cross-talk between channels a sinusoidal signal from 0.6 to 1.7V generated by digital signal generator was imputed into channels 4 of both ADC microcontrollers: first 4 minutes to one ADC microcontroller and the second 4 minutes to the other one. The first channel was loaded with a 5 kω resistor (Figure A5) and in the second case with 1 kω resistor (Figure A6) One can see noticeable cross-talk between channels 4 (top panel) and 5 (bottom panel) in the first case and its complete absence in the second case. The cross-talk between channels 4 and 5 is about in the case of 5 kω load (on both channels) and below 2*10-4 for 1 kω load. Crosstalks between channel 4 and channels other than 5 is negligible for both values of load resistors R=1K,5K,1K 3000 Counts Counts Time, s Figure A5. Example of the correlation between the digitized signals of channel 4 (top panel) and channels 5 (red) (bottom panel). Value of load resistor for channel 4 is 5 kω. 19

20 4000 R=5K,1K,5K 3000 Counts Counts Time, s Figure A6. Example of the correlation between the digitized signals of channel 4 (top panel) and channels 5 (red) (bottom panel). Value of the load resistor for channel 4 is 1 kω. 20

21 CADC board specification Operating voltage: 4-17 VDC Typical power consumption (with attached Colibri module): (Power supply voltage is 6 VDC for the following measured currents.) Peak (during boot) ~ 0.32 A Idle mode (no data recording) ~ 0.15 A Data acquisition mode from ~0.20 A to ~0.26 A Operating temperature range: -40 to +85 C Size (with attached Colibri module): L x W x H: 76 x 48 x 10 mm Weight (with attached Colibri module): 34 grams List of connectors used on the CADC board: Connector Name Manufacturer Part number J1 Power supply etc. Omron Electronics Inc. XF2L A J3 Service board connection TE Connectivity J5 - JTAG connector Omron Electronics Inc. XF2L A J6, J7 ADC input connector TE Connectivity J8 Ethernet connector Samtec Inc. ZF T-WT Software The following examples of software are available for download at SPI bus communication I 2 C bus communication A/D conversion code 21