MC68HC908GR8CP - 8-Bit HC08 MCU 7.5KB Flash 8MHz 28-PDIP | NXP
MPN: MC68HC908GR8CP ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $5.81 | $5.81 |
| 10 | $5.4 | $54.00 |
| 100 | $4.95 | $495.00 |
| 500 | $4.5 | $2,250.00 |
| 1,000 | $4.1 | $4,100.00 |
MC68HC908GR8CP Overview
A microcontroller (MCU) is a single-chip computer that integrates a CPU, RAM, non-volatile program memory (Flash or ROM), and a range of peripherals such as timers, ADC, serial ports, and GPIO. The MC68HC908GR8CP belongs to the HC08 architecture hierarchy: 8-bit microcontroller -> CISC MCU -> embedded controller -> semiconductor. Within the broader NXP/Freescale portfolio, the GR8 family sits in the low-power, general-purpose 8-bit segment aimed at replacing legacy 68HC05 designs while adding Flash and a richer peripheral mix.
Key features include 7.5KB (7.5K x 8) of Flash program memory, 384 bytes of RAM, an internal 8 MHz bus clock, a 6-channel 8-bit ADC, two 16-bit timers, an SCI (UART) port, an SPI port, and up to 21 GPIO lines. The CPU08 core retains HC05 source compatibility while adding a Multiply (MUL) instruction and a higher bus clock. Built-in security includes Flash security and a low-voltage inhibit (LVI) module.
Typical applications include legacy industrial control boards, white-goods user interfaces, low-end appliance controllers, automotive body modules (non-safety), HVAC zone controllers, and educational / development platforms. The PDIP-28 footprint also makes it a friendly target for through-hole prototyping and field service replacements.
When designing with this device, place decoupling capacitors close to VDD/VSS pairs and leave the IRQ/Reset pin accessible for in-system debugging. Note that the GR8 is now in Obsolete / Last Time Buy status - design new platforms around the S08 or S12 families, but treat the GR8 as a long-life replacement for installed HC05/HC08 bases.
Drop-in alternatives for MC68HC908GR8CP — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
MC68HC908GR4CP
✅ Drop-In📋 Reference alternative (not in catalog)
MC68HC908GR8CP Maximum Ratings & Electrical Characteristics
| Core | CPU08 (HC08 family, 8-bit CISC) |
| Bus Clock | 8 MHz (internal) |
| Program Memory | 7.5 KB (7.5K x 8) Flash |
| RAM | 384 bytes |
| Supply Voltage (VDD) | 3.0 V to 5.5 V |
| Operating Temperature | -40 C to +85 C |
| Package | 28-pin PDIP (through-hole) |
| ADC | 8-bit, 6 channels (per datasheet family) |
| Timers | Two 16-bit timer channels (TIM1, TIM2) |
| Communication | SCI (UART), SPI |
| GPIO | Up to 21 shared I/O lines |
| Interrupts | External IRQ, timer, ADC, SCI, SPI sources |
| Security | Flash security byte + Low-Voltage Inhibit (LVI) |
| Mounting Type | Through-Hole (THT) |
| Series | M68HC08 GR family |
MC68HC908GR8CP Pin Configuration
| Pin 1 | RST — Reset input (active low), bidirectional |
| Pin 2 | IRQ — External interrupt request, keyboard wakeup |
| Pin 3 | PTA0 — Port A bit 0 / TIM1 channel 0 |
| Pin 4 | PTA1 — Port A bit 1 / TIM1 channel 1 |
| Pin 5 | PTA2 — Port A bit 2 / TIM2 channel 0 |
| Pin 6 | PTA3 — Port A bit 3 / TIM2 channel 1 |
| Pin 7 | PTA4 — Port A bit 4 |
| Pin 8 | PTA5 — Port A bit 5 |
| Pin 9 | PTA6 — Port A bit 6 |
| Pin 10 | PTA7 — Port A bit 7 |
| Pin 11 | PTB0/AD0 — Port B bit 0 / ADC channel 0 |
| Pin 12 | PTB1/AD1 — Port B bit 1 / ADC channel 1 |
| Pin 13 | PTB2/AD2 — Port B bit 2 / ADC channel 2 |
| Pin 14 | PTB3/AD3 — Port B bit 3 / ADC channel 3 |
| Pin 15 | PTB4/AD4 — Port B bit 4 / ADC channel 4 |
| Pin 16 | PTB5/AD5 — Port B bit 5 / ADC channel 5 |
| Pin 17 | VSS — Ground |
| Pin 18 | VDD — Positive supply (3.0 V to 5.5 V) |
| Pin 19 | PTC0 — Port C bit 0 / SCI TX |
| Pin 20 | PTC1 — Port C bit 1 / SCI RX |
| Pin 21 | PTC2 — Port C bit 2 / SPI SCK |
| Pin 22 | PTC3 — Port C bit 3 / SPI MOSI |
| Pin 23 | PTC4 — Port C bit 4 / SPI MISO |
| Pin 24 | PTC5 — Port C bit 5 / SPI SS |
| Pin 25 | PTD0 — Port D bit 0 |
| Pin 26 | PTD1 — Port D bit 1 |
| Pin 27 | OSC1 — Crystal oscillator input / external clock |
| Pin 28 | OSC2 — Crystal oscillator output |
Typical Applications
MC68HC908GR8CP is suitable for 6 applications: Legacy Industrial Control Boards, White Goods & Appliance User Interfaces, HVAC Zone & Thermostat Controllers, Automotive Body & Comfort Modules (Non-Safety), Educational & Development Platforms, Field Service & Aftermarket Repairs.
Legacy Industrial Control Boards
Replaces aging HC05 controllers on PLC I/O modules, sensor interface boards, and small machine controllers. The MC68HC908GR8CP's 8 MHz CPU08 core executes HC05 object code, while the 7.5 KB Flash provides enough headroom for typical ladder-logic and signal-conditioning firmware. The wide 3.0-5.5 V supply lets it ride 24 V industrial rails after a single LDO drop, and the 28-PDIP through-hole package survives field service rework far better than QFP parts. Engineers servicing installed lines appreciate the familiar MON08 BDM debug interface, which avoids retooling the production line.
Recommended
White Goods & Appliance User Interfaces
Drives button matrices, 7-segment or character LCD displays, buzzer feedback, and relay drivers in washing machines, dishwashers, and microwave ovens. The MC68HC908GR8CP's 21 GPIO and external IRQ with keyboard-wakeup logic are ideal for keypad-debounce firmware, while the SCI/UART link talks to inverter boards and the SPI bus drives LED or character-LCD peripherals. Flash-based program memory simplifies late-stage firmware updates during production. The industrial -40 C to +85 C rating covers appliance environments without premium automotive-grade pricing.
Recommended
HVAC Zone & Thermostat Controllers
Implements the room thermostat, damper actuator, and small fan-coil-unit controllers that surround a central HVAC system. The MC68HC908GR8CP's 8-bit ADC measures thermistor temperature bridges with adequate resolution for setpoint control, while its two 16-bit timers drive triac-fired outputs for line-frequency heater switching. Low power Stop/Wait modes extend battery life in wireless thermostats, and the 5.5 V supply tolerance handles rectified 24 VAC inputs. The PDIP package also supports hand-soldered engineering builds during product development.
Recommended
Automotive Body & Comfort Modules (Non-Safety)
Replaces legacy 68HC05 designs in non-safety body modules such as seat controllers, mirror adjusters, and lighting timers. The MC68HC908GR8CP lacks AEC-Q100 qualification, so it should be reserved for non-safety automotive subsystems that remain inside the cabin thermal envelope (industrial -40 C to +85 C). Designers appreciate Flash-based field firmware updates and the SCI link to body-control network gateways. For safety-critical modules, choose an S12 or S08 automotive-grade part instead, since this part is now Obsolete.
Recommended
Educational & Development Platforms
The HC08 instruction set and abundant reference designs make the MC68HC908GR8CP a popular teaching target in university embedded-systems courses and hobbyist kits. The 28-PDIP package fits 0.600 in DIP sockets on training boards and breadboards, and the MON08 BDM protocol lets students single-step through firmware. CodeWarrior HC08 IDE provides free educational licenses. Although the part is now Obsolete, large installed fleets of training boards keep demand alive, and the GR family datasheet remains a free NXP download for reference.
Recommended
Field Service & Aftermarket Repairs
Service technicians replacing failed MCUs on legacy equipment use the MC68HC908GR8CP as a service-part to keep older machinery running. Because the part is Obsolete, only authorized aftermarket distributors (Rochester Electronics carries franchised stock per the DigiKey listing) hold long-term inventory, often with date-code and traceability documentation. The familiar 28-PDIP outline simplifies socketed swaps on through-hole boards. Engineers planning new designs should treat the GR8 as a service-only stock item and migrate to active S08 or S12 platforms.
Recommended
Recommended Products Summary
Engineering reference data for MC68HC908GR8CP — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | MC68HC908GR4CP | MC68HC908GR8CFA | MC68HC908GP8CFB |
|---|---|---|---|---|
| Package | 28-PDIP (through-hole) | 28-PDIP (through-hole) - same | LQFP-32 (SMT, NOT drop-in) | LQFP-44 (NOT drop-in) |
| Brand | NXP Semiconductors | NXP Semiconductors (same brand) | NXP Semiconductors (same brand) | NXP Semiconductors (same brand) |
| Flash Memory | 7.5 KB | 4 KB (-47%) | 7.5 KB (same) | 8 KB (+7%) |
| Bus Clock | 8 MHz | 8 MHz | 8 MHz | 8 MHz |
| Operating Voltage | 3.0 V to 5.5 V | 3.0 V to 5.5 V | 3.0 V to 5.5 V | 3.0 V to 5.5 V |
| Temperature Grade | -40 C to +85 C (industrial) | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C |
| Lifecycle Status | Obsolete | Obsolete | Obsolete | Obsolete |
Key Differentiators
- True through-hole 28-PDIP option in the HC08 family (vs MC68HC908GR8CFA)
- Maximum Flash density (7.5 KB) within the GR family (vs MC68HC908GR4CP)
- Lower pin count than the GP family siblings (vs MC68HC908GP8CFB)
Design Notes
Place a 0.1 uF decoupling capacitor directly between each VDD/VSS pair as close to the IC pins as possible, plus a single 4.7-10 uF bulk tantalum or ceramic cap at the supply entry point. The on-chip LVI (low-voltage inhibit) module generates a clean power-on reset; however, the IRQ/RST lines must remain low during power ramp-up to avoid spurious interrupts. Estimated: at fBUS = 8 MHz and VDD = 5.0 V, the HC08 core draws roughly 10-15 mA active and under 50 uA in Stop mode.
Do not confuse the GR family suffix codes: 'CP' = industrial / PDIP-28, 'CB' = industrial / SOIC-28, 'CFA' = industrial / LQFP-32, 'VFA' = extended-temp / LQFP-32, and 'MFA' = automotive. The 'GR8' label means 7.5 KB Flash; the 'GR4' is the same die with 4 KB Flash and identical pinout. Engineers commonly misorder the GR4 thinking it is the higher-density part, so always verify the Flash size from the mask set rather than the family name.
The 28-PDIP package has a theta_JA of approximately 70-80 C/W in still air. At 5 V VDD and 8 MHz the part dissipates around 50-70 mW, yielding a junction temperature rise of only 4-5 C above ambient - well within the -40 C to +85 C industrial rating. For closed-enclosure designs with no airflow, derate by adding a small clip-on heatsink if multiple peripherals also dissipate heat on the same board.
Route the OSC1/OSC2 crystal traces short and symmetric, with a ground guard ring on either side to suppress coupling from high-current PWM traces. Keep analog ADC inputs (PTB0-PTB5/AD0-AD5) routed away from SCI TX/RX lines and bypassed with small RC filters if they share ground with the switching regulator. Avoid running digital signal traces under the crystal area to minimize stray capacitance drift.
The SCI/UART lines need series resistors (~100 ohm) when connecting to long cables or RS-232 transceivers to damp ringing. The SPI bus should have a pull-up on SS to prevent false slave selection at reset; MOSI/MISO lines should be kept under 100 mm to avoid reflections at 8 MHz bus speeds. The IRQ pin is sensitive to noise - add a 100 nF bypass cap directly at the pin when used for keyboard wakeup.
Compliance Information
Part originally launched as Motorola/Freescale before NXP acquisition. RoHS, REACH, and lead-free status not confirmed in verified data; AEC-Q100 not qualified (industrial grade only). For safety-critical automotive use, migrate to the AEC-Q100-qualified S08/S12 platforms.
