1. Figure out which are the programmable devices on the board. The devices on the board are not all programmable within the system. For example, parallel devices are usually not allowed to do so. For programmable devices, the serial programming capability of the ISP is essential to maintain design flexibility.
2. Check the programming specifications for each device to determine which pins are required. This information can be obtained from the device manufacturer or downloaded from the Internet. In addition, field application engineers can provide device and design support and are a good resource.
3. Connect the programming pins in order to use the pins on the control board. Verify that the programmable pins are connected to connectors or test points on the board in this design. These are required for in-circuit testers (ICT) or ISP programmers used in production.
4. Avoid contention. Verify that the signals required by the ISP are not connected to other hardware that would conflict with the programmer. Look at the load of the line. There are some processors that can drive light emitting diodes (LEDs) directly, however, most programmers cannot do this yet. If the inputs/outputs are shared, then this can be a problem. Please pay attention to the monitor timer or reset signal generator. If a random signal is sent by the monitor timer or reset signal generator, then the device may be incorrectly programmed.
5. Determine how the programmable device is powered up during the manufacturing process. The target board must be powered up in order to be programmed in the system. We also need to determine the following issues.
(1) What voltage is required? In programming mode, components usually require a different voltage range than in normal operating mode. If the voltage is higher during programming, then it must be ensured that this higher voltage will not cause damage to other components.
(2) Some devices must be verified at high and low levels to ensure that the device is programmed correctly. If this is the case, then the voltage range must be specified. If a reset generator is available, check the reset generator first, as it may attempt to reset the device when performing a low voltage check.
(3) If this device requires a VPP voltage, then provide the VPP voltage on the board or use a separate power supply to power it during production. The processor requiring the VPP voltage will share this voltage with the digital input/output lines. Make sure that other circuits connected to the VPP can operate at higher voltages.
(4) Do I need a monitor to see if the voltage is within the specifications of the device? Please make sure the safety device is effective to keep these power supplies within the safety range.
(6) Figure out what kind of equipment to use for programming, as well as for design. During the test phase, if the board is placed on a test fixture for programming, then the pins can be connected via a pin bed. Another way is that if you need to use a rack tester, and to run a special test program, it is best to use a connector on the side of the board to connect, or use a cable to connect.
7. Come up with some creative information tracking measures. The practice of adding configuration-specific data at the back of the line is becoming more common. In the programmable device effective use of time, it can be made into a “smart” device. Adding product-related information to the product, such as serial number, MAC address, or production data, makes the product more useful, easier to maintain and upgrade, or easier to provide warranty service, and also allows the manufacturer to collect useful information over the useful life of the product. Many “smart” products have this tracking capability by adding a simple and inexpensive EEPROM that can be programmed with data from the production line or the field.
A well-designed circuit that is suitable for the final product can also pose a barrier to ISP implementation during production. Therefore, the board needs to be modified to make it best suited for the ISP on the production line and end up with a good board.
Post time: Apr-01-2022