Logic/Test Probe

LOGIC/TEST PROBE
Part #LP-1 - $139.00
The LP-1 Logic/Test probe is a tool designed to identify in-circuit programming issues before communication problems occur. In-circuit (the parts are not removed from the board) reading and programming of serial eeproms and microcontrollers requires that two conditions be met before successful communication with the part can occur. The first condition is that the programming equipment generate signals sufficient to drive the appropriate part pins. The second is that valid logic levels (0 or 1) are present on pins necessary for communication to be established. This is most common with microcontrollers. The LP-1 allows you to test for both issues before you encounter a part with which you cannot communicate.

Andromeda Research manufacturers in-circuit adapters which are designed to allow reading and programming of serial eeproms, serial frams, serial flash eproms and microcontrollers. An in-circuit part is a part which remains soldered to the circuit assembly. As such it remains connected to other electronic components on the same assembly. The challenge with in-circuit programming is to make the target device, memory or microcontroller, function as if it is not connected to any other components. This requires that the signals which drive the target device force the required pins to valid logic levels without damaging the surrounding connected components. A valid logic level is a voltage which the target part properly interprets as a logic 1 or logic 0. Andromeda Research in-circuit adapters perform this function. If, however, a component or connection exhibits and excessive load which does not allow a valid logic level to be reached, the in-circuit adapter will limit the current to the target assembly to prevent damage but in-circuit reading/programming will not be possible unless the offending pin is isolated. This is the purpose of the LP-1, to locate the target pin(s) which exhibit the excessive load. The LP-1 Logic/Test probe performs two functions: 1. It generates voltage levels which can be applied to a target chip pin. If the pin cannot be driven to a valid logic level the probe will provide a visual indication. 2. There are target parts, usually microcontrollers, which require specific pins to be at specified logic levels in order for the part to communicate. The LP-1 will indicate if a target chip pin is already at the correct logic level. (customer comment)

TWO MODES - TEST and PROBE
The LP-1 has two modes of operation; TEST and PROBE. The MODE is set using a small slide switch close to the probe tip. The probe is designed to be held in one hand much like a fat pencil. The probe tip is a hardened steel, needle point which can penetrate sealant on the target pin while lodging in the pin body which prevents sliding. The probe uses a three color LED as the visual indicator. TEST MODE - When in the TEST mode the probe tip produces the same drive signal used by the in-circuit adapters. The LED will alternately blink (RED/GREEN). When the probe tip is touched to the target pin the LED will stop blinking (lock on RED or GREEN) if the pin cannot be driven to a valid logic level. If the LED locks this indicates that this pin on the target chip must be isolated for successful in-circuit programming. If a valid logic level can be applied the LED will continue to blink. PROBE MODE - With the LP-1 set to PROBE the LED will glow YELLOW when the probe tip is not touching a valid logic level. To determine the logic level of a target chip pin touch the probe tip to the pin. The LED will change from YELLOW to RED for a logic 1 or GREEN for a logic 0. This allows you to determine the logic level (0 or 1) of any target chip pin.

POWERING THE PROBE
The LP-1 may receive power from three different sources. The first and most conveniet is directly from the surface mount probes which connect to the target chip. Each surface mount probe has an alternate connection pin on the opposite of the probe body. This alternate connection pin allows the LP-1 power leads to attach. Once attached the LP-1 will begin to function as soon as the in-circuit adapter is switch on (ACOM2) or powered on by the programming unit (ASERSM1A). The second option is to power the LP-1 from the ACCESSORY CONNECTOR on the programming unit. The ACCESSORY CONNECTOR provides a fixed 5 VOLT source. This may be more convenient if you do not wish to attach the LP-1 to the same probes which are attached to the part. The third option is to connect the probe power leads to alternate power connections on the target assembly using the supplied WHITE (+) and BLACK (-) surface mount mount probes. This option allows you to use the LP-1 in a stand alone mode if you are powering the target assembly from a separate power supply.