Header Board Specification WHY DO I NEED A HEADER TO DEBUG Some PIC microcontrollers, particularly low pin count devices (with 20 pins or less), generally must use a header for debugging. This is done to free up I/O lines for your application and to make production parts more affordable. Optional headers are also available for high pin count devices (with 64 pins or higher). Debugging requires a two-line connection (plus VDD, VSS and VPP) to communicate with the device. In a high pin count device, losing a few I/O lines is generally not a prob- lem for most designs. But in a low pin count device, it can be a critical problem. Imagine having to do an 8-pin design where there are only 5 I/Os, having used up 2 I/Os just for debugging Headers are also used to save you money. In high pin count devices, adding debug- ging to the silicon can generally be done at little or no cost since the silicon is already fairly large. However, low pin count devices are low cost specifically because they use very little silicon. So, adding debugging circuitry on-board these parts would add sig- nificant cost since it would raise the amount of silicon used by a considerable percent- age. The header places the cost for debugging up front and frees your production parts from the extra cost of an unused debug module. Microchip also makes optional debug modules, usually for high pin count devices. The module is optional because you can still do basic debugging without a header, but if you use one, you get back I/O lines, and may also gain additional debugging features. Only certain devices can use an optional header, see the device page on our website for details. Microchip lists what header must be ordered to work with your device, if one is required. Simply consult the device page on our website, or our other ordering guides. Note that in all cases, devices can be programmed in circuit (called ICSP) with very few exceptions. Even devices without an internal debug feature can still be pro- grammed by connecting the programming/debugging tool to the in-circuit programming lines. These devices simply cannot perform debugging without a header. FIGURE 1: PRODUCTION DEVICE VS. HEADER DEVICE (-ICE/-ICD) VDD 1 20 ENABLE ICDCLK 19 2 ICDMCLR ICDDATA 3 3 18 VDD Vss 1 14 1 2 4 17 2 13 5 16 3 12 VDD Vss 6 15 4 11 JP1 14 7 5 10 13 8 6 9 12 9 7 8 10 11 ICD NC Production Device -ICE/-ICD Device To Tool Connector on Header Board 2010 Microchip Technology Inc. DS51292S-page 1Header Board Specification DEBUG DETAILS Next generation in-circuit emulators (such as the MPLAB REAL ICE in-circuit emulator) and in-circuit debuggers work with devices that have on-chip debug circuitry. Sometimes the actual production device will have this circuitry and sometimes a special version of this device is required or available for code debugging. This special version of the chip, with the suffix -ICD or -ICE, is mounted on a header board (Figure 2). Note: ICE/ICD devices are only used on the header they are not sold separately. FIGURE 2: DEBUG OPTIONS Production Device without Production Device with On-Board Debug Circuitry On-Board Debug Circuitry VDD Vss Rx1/DAT Rx0/CLK MCLR/VPP Debug Circuitry No debug capability. Debug capability available. Header required for debug. However, header can provide dedicated resources for debug. Header board with additional ICE/ICD Device with On-board Debug circuitry to support debug Circuitry, Dedicated Debug Pins and functions. (sometimes) Dedicated Debug Memory. S1 VSS J1 VDD DAT MCLR CLK VPP Rx1 Rx0 TP1 TP2 ICE/ Debug TP3 ICD Memory Device Debug Circuitry In general, ICE devices are designed for next-generation in-circuit emulator use and ICD devices are designed for in-circuit debugger use. However, ICE devices may be used with an in-circuit debugger and ICD devices may be used with a next-generation in-circuit emulator, but will provide only basic ICD functionality. To determine what device resources must be dedicated to debugging for either a device with on-board debug capability or the special ICE/ICD device, see the Resources used by ... section of the in-circuit emulator or in-circuit debugger on-line help file. DS51292S-page 2 2010 Microchip Technology Inc. ON