APPLICATION NOTE Atmel AVR32715: AVR UC3B 32-bit Microcontroller Schematic Checklist Atmel AVR UC3 32-bit Microcontroller Features • • • • • Power circuit Reset circuit Clocks and crystal oscillators USB connection JTAG and Nexus debug ports Introduction A good hardware design comes from a proper schematic. Since Atmel® AVR® UC3B series devices have a fair number of pins and functions, the schematic for these devices can be large and quite complex. This application note describes a common checklist which should be used when starting and reviewing the schematics for an AVR UC3B series design. 32095E−AVR UC3−08/2013 Table of Contents 1. Power Circuit ........................................................................................ 3 1.1 Single 3.3V Power Supply ................................................................................. 3 1.2 Dual 3.3V and 1.8V Power Supply .................................................................... 4 1.3 ADC Reference Power Supply .......................................................................... 5 1.4 No ADC Power Supply ...................................................................................... 6 2. Reset Circuit ........................................................................................ 7 3. Clocks and Crystal Oscillators ............................................................. 8 3.1 External Clock Source ....................................................................................... 8 3.2 Crystal Oscillator ............................................................................................... 8 4. USB Connection .................................................................................. 9 4.1 Not Used ........................................................................................................... 9 4.2 Device Mode, Powered from Bus Connection ................................................... 9 4.3 Device Mode, Self Powered Connection ......................................................... 10 4.4 Host/OTG Mode, Power from Bus Connection ............................................... 11 5. JTAG and Nexus Debug Ports ........................................................... 12 5.1 JTAG Port Interface ........................................................................................ 12 5.2 Nexus Port Interface ....................................................................................... 13 6. GPIO Pin Used by Default USB DFU Bootloader .............................. 15 7. Suggested Reading ........................................................................... 16 7.1 Device Datasheet ............................................................................................ 16 7.2 Evaluation Kit Schematic ................................................................................ 16 8. Revision History ................................................................................. 17 Atmel AVR32715: AVR UC3B 32-bit Microcontroller Schematic Checklist [APPLICATION NOTE] 32095E−AVR UC3−08/2013 2 1. Power Circuit 1.1 Single 3.3V Power Supply Figure 1-1. Single 3.3V power example schematic. Common for pin groups Close to device (every pin) Close to pin VDDIO DC/DC converter 4.7µF 100nF 33nF VDDIN 3.33.3 volt volt 4.7µF 100nF 33nF Voltage regulator VDDOUT 2.2µF 470pF VDDCORE 2.2µF 100nF 33nF 2.7nF VDDPLL 2.2µF Table 1-1. 33nF 2.7nF Single 3.3V power supply checklist. Signal name Recommended pin connection Description VDDIO 3.0V to 3.6V Decoupling/filtering capacitors 33nF (1)(2), 100nF (1)(3) and 4.7µF (1) Powers I/O lines and USB transceiver. 3.0V to 3.6V Decoupling/filtering capacitors 33nF (1)(2), 100nF (1)(3) and 4.7µF (1) Powers on-chip voltage regulator. Decoupling/filtering capacitors 470pF (1)(2) and 4.7µF (1) Output of the on-chip 1.8V voltage regulator. VDDIN VDDOUT Decoupling/filtering capacitors must be added to improve startup stability and reduce source voltage drop. Decoupling/filtering capacitors must be added to improve startup stability and reduce source voltage drop. Decoupling/filtering capacitors must be added to guarantee 1.8V stability. VDDCORE 1.65V to 1.95V Connected to VDDOUT Decoupling/filtering capacitors 2.7nF (1)(2), 33nF (1)(3), 100nF (1) and 4.7µF (1) Powers device, flash logic and on-chip RC. Decoupling/filtering capacitors must be added to improve startup stability and reduce source voltage drop. Atmel AVR32715: AVR UC3B 32-bit Microcontroller Schematic Checklist [APPLICATION NOTE] 32095E−AVR UC3−08/2013 3 Signal name Recommended pin connection Description VDDPLL 1.65V to 1.95V Connected to VDDOUT Decoupling/filtering capacitors 2.7nF (1)(2), 33nF (1)(3) and 4.7µF (1) Powers the PLL. Notes: 1.2 Decoupling/filtering capacitors must be added to improve startup stability and reduce source voltage drop. 1. These values are given only as a typical example. 2. Decoupling capacitor should be placed as close as possible to each pin in the signal group, vias should be avoided. 3. Decoupling capacitor should be placed close to the device for each pin in the signal group. Dual 3.3V and 1.8V Power Supply Figure 1-2. Dual 3.3V and 1.8V power example schematic. DC/DC converter Common for pin groups Close to device (every pin) Close to pin VDDIO 4.7µF 3.33.3 volt volt 100nF 33nF VDDIN Voltage regulator VDDOUT DC/DC converter VDDCORE 1.83.3 volt volt 2.2µF 100nF 2.7nF VDDPLL 2.2µF Table 1-2. 33nF 33nF 2.7nF Dual 3.3V and 1.8V power supply checklist. Signal name Recommended pin connection Description VDDIO 3.0V to 3.6V Decoupling/filtering capacitors 33nF (1)(2), 100nF (1)(3) and 4.7µF (1) Powers I/O lines and USB transceiver. VDDIN Connected to ground. On-chip voltage regulator not in use. VDDOUT Connected to ground. On-chip voltage regulator not in use. Decoupling/filtering capacitors must be added to improve startup stability and reduce source voltage drop. Atmel AVR32715: AVR UC3B 32-bit Microcontroller Schematic Checklist [APPLICATION NOTE] 32095E−AVR UC3−08/2013 4 Signal name Recommended pin connection Description VDDCORE 1.65V to 1.95V Decoupling/filtering capacitors 2.7nF (1)(2), 33nF (1)(3), 100nF (1) and 2.2µF (1) Powers device, flash logic and on-chip RC. 1.65V to 1.95V Decoupling/filtering capacitors 2.7nF (1)(2), 33nF (1)(3) and 2.2µF (1) Powers the PLL. VDDPLL Notes: 1.3 Decoupling/filtering capacitors must be added to improve startup stability and reduce source voltage drop. Decoupling/filtering capacitors must be added to improve startup stability and reduce source voltage drop. 1. These values are given only as a typical example. 2. Decoupling capacitor should be placed as close as possible to each pin in the signal group, vias should be avoided. 3. Decoupling capacitor should be placed close to the device for each pin in the signal group. ADC Reference Power Supply The following schematic checklist is only necessary if the design is using the internal analog to digital converter. Figure 1-3. ADC reference power supply example schematic. Close to device (every pin) Close to pin VDDANA DC/DC converter 100nF 33nF ADVREF 3.33.3 volt volt Table 1-3. ADC reference power supply checklist. Signal name Recommended pin connection Description VDDANA 3.0V to 3.6V Decoupling/filtering capacitors 33nF (1)(2) and 100nF (1)(3) Powers on-chip ADC. 2.6V to VDDANA. Connect with VDDANA. ADVREF is a pure analog input. ADVREF Notes: Decoupling/filtering capacitors must be added to improve startup stability and reduce source voltage drop. 1. These values are given only as a typical example. 2. Decoupling capacitor should be placed as close as possible to each pin in the signal group, vias should be avoided. 3. Decoupling capacitor should be placed close to the device for each pin in the signal group. Atmel AVR32715: AVR UC3B 32-bit Microcontroller Schematic Checklist [APPLICATION NOTE] 32095E−AVR UC3−08/2013 5 1.4 No ADC Power Supply The following schematic checklist is only necessary if the design is not using the internal analog to digital converter. Figure 1-4. No ADC power supply example schematic. DC/DC converter VDDANA 3.33.3 volt volt ADVREF Table 1-4. No ADC power supply checklist. Signal name Recommended pin connection VDDANA 3.0V to 3.6V ADVREF Connected to ground. Description Atmel AVR32715: AVR UC3B 32-bit Microcontroller Schematic Checklist [APPLICATION NOTE] 32095E−AVR UC3−08/2013 6 2. Reset Circuit Figure 2-1. Reset circuit example schematic. Table 2-1. Reset circuit checklist. Signal name Recommended pin connection Description RESET Can be left unconnected in case no reset from the system needs to be applied to the product. The RESET_N pin is a Schmitt input and integrates a permanent pull-up resistor to VDDIO. Atmel AVR32715: AVR UC3B 32-bit Microcontroller Schematic Checklist [APPLICATION NOTE] 32095E−AVR UC3−08/2013 7 3. Clocks and Crystal Oscillators 3.1 External Clock Source Figure 3-1. External clock source schematic. Table 3-1. 3.2 External clock source checklist. Signal name Recommended pin connection Description XIN Connected to clock output from external clock source. Up to VDDIO volt square wave signal up to 50MHz. XOUT Can be left unconnected or used as GPIO. Crystal Oscillator Figure 3-2. Crystal oscillator example schematic. Table 3-2. Crystal oscillator checklist. Signal name XIN XOUT Notes: Recommended pin connection Biasing capacitor 22pF (1)(2) Biasing capacitor 22pF (1)(2) Description External crystal between 0.4MHz and 20MHz. 1. These values are given only as a typical example. The capacitance C of the biasing capacitors can be computed based on the crystal load capacitance CL and the internal capacitance Ci of the MCU as follows: C = 2 (CL – Ci) The value of CL can be found in the crystal datasheet and the value of Ci can be found in the MCU datasheet. 2. Decoupling capacitor should be placed as close as possible to each pin in the signal group, vias should be avoided. Atmel AVR32715: AVR UC3B 32-bit Microcontroller Schematic Checklist [APPLICATION NOTE] 32095E−AVR UC3−08/2013 8 4. USB Connection 4.1 Not Used When the USB interface is not used, D+ and D- should be connected to ground. 4.2 Device Mode, Powered from Bus Connection Figure 4-1. USB in device mode, bus powered connection example schematic. VDD 3.3 volt regulator VBUS VBUS D- D+ USB_VBOF D39 ohm D+ 39 ohm USB_ID ID GND Table 4-1. USB bus powered connection checklist. Signal name Recommended pin connection Description USB_VBOF Can be left unconnected. USB power control pin. VBUS Directly to connector. USB power measurement pin. D- 39Ω series resistor. Placed as close as possible to pin. Negative differential data line. D+ 39Ω series resistor. Placed as close as possible to pin. Positive differential data line. USB_ID Can be left unconnected. Mini connector USB identification pin. Atmel AVR32715: AVR UC3B 32-bit Microcontroller Schematic Checklist [APPLICATION NOTE] 32095E−AVR UC3−08/2013 9 4.3 Device Mode, Self Powered Connection Figure 4-2. USB in device mode, self powered connection example schematic. USB_VBOF VBUS VBUS D- D+ D39 ohm D+ 39 ohm USB_ID ID GND Table 4-2. USB self powered connection checklist. Signal name Recommended pin connection Description USB_VBOF Can be left unconnected. USB power control pin. VBUS Directly to connector. USB power measurement pin. D- 39Ω series resistor. Placed as close as possible to pin. Negative differential data line. D+ 39Ω series resistor. Placed as close as possible to pin. Positive differential data line. USB_ID Can be left unconnected. Mini connector USB identification pin. Atmel AVR32715: AVR UC3B 32-bit Microcontroller Schematic Checklist [APPLICATION NOTE] 32095E−AVR UC3−08/2013 10 4.4 Host/OTG Mode, Power from Bus Connection Figure 4-3. USB host and OTG powering connection example schematic. Table 4-3. USB host and OTG powering connection checklist. Signal name Recommended pin connection Description USB_VBOF GPIO connected to VBUS 5.0V regulator enable signal. USB power control pin. VBUS Directly to connector. USB power measurement pin. D- 39Ω series resistor. Placed as close as possible to pin. Negative differential data line. D+ 39Ω series resistor. Placed as close as possible to pin. Positive differential data line. USB_ID GPIO directly connected to connector, mandatory in OTG mode. Mini connector USB identification pin. For OTG it will be tied to ground in host mode, and left floating in device mode. Pull-up on GPIO pin must be enabled. Atmel AVR32715: AVR UC3B 32-bit Microcontroller Schematic Checklist [APPLICATION NOTE] 32095E−AVR UC3−08/2013 11 5. JTAG and Nexus Debug Ports 5.1 JTAG Port Interface Figure 5-1. JTAG port interface example schematic. Table 5-1. JTAG port interface checklist. Signal name Recommended pin connection Description TMS Test mode select, sampled on rising TCK. TDO Test data output, driven on falling TCK. TCK Test clock, fully asynchronous to system clock frequency. RESET Device external reset line. TDI Test data input, sampled on rising TCK. EVTO Event output, not used. Atmel AVR32715: AVR UC3B 32-bit Microcontroller Schematic Checklist [APPLICATION NOTE] 32095E−AVR UC3−08/2013 12 5.2 Nexus Port Interface Figure 5-2. Nexus port interface example schematic. Atmel AVR32715: AVR UC3B 32-bit Microcontroller Schematic Checklist [APPLICATION NOTE] 32095E−AVR UC3−08/2013 13 Table 5-2. Nexus port interface checklist. Signal name Recommended pin connection Description TDI Test data input, sampled on rising TCK. TMS Test mode select, sampled on rising TCK. TCK Test clock, fully asynchronous to system clock frequency. TDO Test data output, driven on falling TCK. RESET Device external reset line. EVTI Event input. MDO[0:5] Trace data output. EVTO Event output. MCK0 Trace data output clock. MSE[0:1] Trace frame control. Atmel AVR32715: AVR UC3B 32-bit Microcontroller Schematic Checklist [APPLICATION NOTE] 32095E−AVR UC3−08/2013 14 6. GPIO Pin Used by Default USB DFU Bootloader All AVR UC3B series devices are shipped with default USB DFU Bootloader. If this Bootloader is going to be used in the application, a pull up or pull down resistor (depending up on IO Pin Condition level in the user page configuration word) must be connected to specific GPIO pin. The logic level of this GPIO pin will be used as hardware condition to enter into the Bootloader mode. The IO condition pin used in default USB DFU Bootloader (For UC3B Device) is PA13. By default, logic low condition is used to enter into Bootloader mode. Normally Push button in Atmel AVR UC3B Evaluation kits is used for this purpose. Following schematic is a typical example for this. Figure 6-1. Bootloader GPIO pin – pull-up resistor typical example schematic. VDDIO 10k ohm PA13 100nF To know more about the USB DFU Bootloader functionalities and its usage, please refer to the application note AVR32784: AVR UC3 USB DFU Bootloader. Atmel AVR32715: AVR UC3B 32-bit Microcontroller Schematic Checklist [APPLICATION NOTE] 32095E−AVR UC3−08/2013 15 7. Suggested Reading 7.1 Device Datasheet The device datasheet contains block diagrams of the peripherals and details about implementing firmware for the device. The datasheet is available on http://www.atmel.com/products/microcontrollers/avr/default.aspx?tab=documents. 7.2 Evaluation Kit Schematic The evaluation kit EVK1101 contains the full schematic for the board; it can be used as a reference design. The schematic is available on http://www.atmel.com/products/microcontrollers/avr/default.aspx?tab=tools. Note that capacitors are soldered on the NEXUS trace data output lines on the EVK1101. This may cause speed limitations. In order to not have this limitation the capacitors has to be removed. Atmel AVR32715: AVR UC3B 32-bit Microcontroller Schematic Checklist [APPLICATION NOTE] 32095E−AVR UC3−08/2013 16 8. Revision History Doc. rev. Date Comments 32095E 08/2013 New document template. Description for VDDPLL is corrected, external oscillator range is updated, and default bootloader pin is mentioned. 32095D 12/2008 New document template. Bugs fixed. 32095C 09/2008 XIN voltage corrected. 32095B 04/2008 Several updates. 32095A 01/2008 Initial document release. Atmel AVR32715: AVR UC3B 32-bit Microcontroller Schematic Checklist [APPLICATION NOTE] 32095E−AVR UC3−08/2013 17 Atmel Corporation Atmel Asia Limited Atmel Munich GmbH Atmel Japan G.K. 1600 Technology Drive Unit 01-5 & 16, 19F Business Campus 16F Shin-Osaki Kangyo Building San Jose, CA 95110 BEA Tower, Millennium City 5 Parkring 4 1-6-4 Osaki, Shinagawa-ku USA 418 Kwun Tong Road D-85748 Garching b. Munich Tokyo 141-0032 Tel: (+1)(408) 441-0311 Kwun Tong, Kowloon GERMANY JAPAN Fax: (+1)(408) 487-2600 HONG KONG Tel: (+49) 89-31970-0 Tel: (+81)(3) 6417-0300 www.atmel.com Tel: (+852) 2245-6100 Fax: (+49) 89-3194621 Fax: (+81)(3) 6417-0370 Fax: (+852) 2722-1369 © 2013 Atmel Corporation. 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